Abstract

OENO One

Cover crops in viticulture. A systematic review (2): Implications on vineyard agronomic performance

¹ INTIA, Edificio de Peritos, Villava, Navarra, Spain ² Departement of Agronomy, Biotechnology and Food Science, Univ. Pública de Navarra UPNA, Pamplona, Navarra, Spain

Abad

Javier

Mendoza

IranzuHermosode

² Marín

Diana

² Santesteban

LuisOrcaray1andLuisGonzaga

Abstract

The present systematic review aims to provide an overview of the impact of cover crops on vegetative growth and the productive parameters of vineyards.

A systematic review was made on Scopus-index journals dating from 1999 to 2018. The selection was made at the same time by two different researchers, who selected a total of 272 published papers related to cover crops in vineyards. Each article was categorised according to its theme and a metadata database was created, considering all relevant information from an agronomic point of view for each article.

It can be concluded from the review that the use of cover crops can reduce vine vegetative growth, which in turn can help keep the incidence of fungal diseases (like grey mould) at a low level. In general, this practice does not have a clear effect on vineyard yield or grape juice parameters, like total soluble solids (TSS) or titratable acidity (TA). Cover crops can decrease vineyard pests to a certain extent, especially Cicadellidae. Cover crops can sometimes sporadically cause water stress in the vineyard, but only during the summer months.

This review allowed us to summarise available information on cover crops and their effects on vineyard agronomic performance in a systematic way. Such information can be used to help select the most suitable cover, based on specific vineyard objectives and growing conditions.

Keywords: Vitis vinifera L., yield, water status, grape composition, pest and disease

Introduction

Cover crops are one of the most appealing options for soil management in vineyards, because- as was shown in our companion paper (Abad et al., 2021) - they increase soil organic carbon, improve water infiltration and aggregate stability, reduce soil erosion and greenhouse gas emissions, and increase biodiversity in the vineyard. Nevertheless, as vines and cover crops coexist in the same space, they compete for nutrients and water at certain moments in the season, which can directly affect vineyard performance. Such competition can result in changes to shoot growth and leaf activity, which in turn can seriously affect shoot fertility, fruit set, berry development, susceptibility to pests and diseases, yield, and grape composition (Ibañez Pascual, 2013).

The intensity and implications of the aforementioned effects depend highly on many factors, such as cover crop features, soil type, climate and other vineyard characteristics. We therefore carried out a systematic review of research results obtained in recent decades to determine the main agronomic effects of cover crops in vineyards and the factors that modulate them. In this article, the second part of the review results is presented; only nutrition was included in the first part, as it was considered to be highly linked to other soil processes described therein.

Published data sourcing and selection

The methodology applied for this systematic review is detailed in the article, “Cover crops in viticulture. A systematic review (1): implications on soil characteristics and vineyard biodiversity” (Abad et al., 2021). In short, a systematic review can be defined as including (1) a research question, (2) sources that were searched with a reproducible search strategy (naming of databases, naming of search platforms/engines, search date and complete search strategy), (3) inclusion and exclusion criteria, and (4) selection (screening) methods (Krnic Martinic et al., 2019). As such, the main features of the systematic review we performed on the implication of cover crops in vineyards are summarised below.

The Scopus database was used, with search query TITLE-ABS-KEY (“cover crop” OR “green cover” OR “ground cover” OR “tillage”) AND TITLE-ABS-KEY (“wine” OR “vitis” OR “vineyard” OR “grapevine” OR “grape”). A total number of 584 published papers were obtained (search day: 20 November 2018). Two people worked independently from each other on the selection process in several steps with a final number of 272 papers being selected. The following data were extracted from the selected papers:

▸ Location

▸ Vineyard: scion variety and rootstock, planting frame, age and vine training

▸ Experiment duration

▸ Cover crop characteristics (sown or spontaneous, monoculture or crop mixture, species, cover crop and row management)

▸ Climate: an illustrative classification was performed; cold (annual average Tª below 12 ºC), mild (annual average Tª between 12 and 15 ºC) and warm climate (annual average Tª above 15 ºC)

▸ Cultural practices: irrigation (yes/no) and fertilisation (yes/no)

▸ Soil: texture, organic matter percentage (% OM) and studied horizons

The following sections provide information related to vineyard agronomic performance, whereas the aforementioned companion paper outlined soil characteristics and environmental aspects. Both papers together are a compilation of most of the factors that should condition the choice of soil management in a vineyard. It should be noted that other factors, such as spring frost risk, the necessity of soil amendments once the vineyard is established, or risk of excessive competition with young vines, need to be considered before choosing cover crop as the best solution; however, they were not considered in the systematic review as information on them was not available in the selected papers.

Vegetative development

Ensuring optimal vegetative development is one of the key issues for successful grape growing, with a balanced number and disposition of leaves being required. Although minimum leaf development is required to guarantee carbohydrate supply to all plant organs, excessive growth can be detrimental, as it may cause reduced fruit set (Dardeniz et al., 2008; Parker et al., 2016), increased susceptibility to fungal diseases (Valdés-Gómez et al., 2011) and delayed ripening (Smart et al., 2017). Therefore, it is of great interest to determine the ways in which cover crops can impact vine growth.

The effect of cover crops on vine vegetative growth – mostly evaluated by pruning weight measurement - was analysed in 51 of the selected articles. None of these articles reported that an increase in vegetative development was associated with the introduction of a cover crop, and only 3 studies (6 % of the cases) showed no changes in pruning weight due to its presence. Thus, the use of cover crops mostly caused a reduction in growth (Table 1). However, in 23 articles (45 %) the reduction in pruning weight was relatively small (by < 20 %), while in the remaining 25 articles (49 %) this reduction was > 20 %. When the potential impact of climate conditions was analysed (Figure 1), it was observed that vineyards in warmer regions showed a more pronounced decrease in growth than those in cooler areas.

Table Table 1. Impact of cover crop on vine vegetative growth (pruning weight) compared to tilled or to herbicide applied in the row.

titre du tableau

No trend

1 Costello (2010b) = 2 Jordan et al. (2016) = 3 Wilson et al. (2017) =

Slightly negative

4 DeVetter et al. (2015) +(T)/- 12 Karl et al. (2016)** =/-- 20 Ingels et al. (2005)* -(T)/--

5 Krohn and Ferree (2004) +(T)/-- 13 Smith et al. (2008) =/- 21 Reynolds et al. (2006)** -(T)/--

6 Sweet and Schreiner (2010)* +(T)/-- 14 Klodd et al. (2016) - (T) 22 Ripoche et al. (2011)* - (T)/--

7 Tourte et al. (2008) =/-(T) 15 Steenwerth et al. (2016) - (T) 23 Giese et al. (2016) -

8 Lopes et al. (2008) =/-- 16 Coniberti et al. (2018a) - (T)/- 24 Steenwerth et al. (2013) -

9 Mercenaro et al. (2014) =/- 17 Monteiro and Lopes (2007) - (T)/- 25 Vrsic et al. (2011) -

10 Pérez-Álvarez et al. (2015b) =/- 18 Muscas et al. (2017)* - (T)/- 26 Pérez et al. (2018) -/--

11 Trigo-Córdoba et al. (2015) =/- 19 Tomaz et al. (2015) - (T)/-

Negative

27 Rodriguez-Lovelle et al. (2000b) +(T)/--- 36 Palliotti et al. (2007) -- 45 Coletta et al. (2013) ---

28 Delpuech and Metay (2018)* =/-- 37 Pou et al. (2011)* -- 46 Coniberti et al. (2017) ---

29 Reeve et al. (2016) -/--- 38 Valdés-Gómez et al. (2011) -- 47 Gontier et al. (2014) ---

30 Coniberti et al. (2018b) -- 39 Caspari et al. (1997) --/--- 48 Hatch et al. (2011) ---

31 De Pascali et al. (2014) -- 40 Guilpart et al. (2017) --/--- 49 Olmstead et al. (2012) ---

32 Giese et al. (2015) -- 41 Mattii et al. (2005) --/--- 50 Toci et al. (2012) ---

33 Hickey et al. (2016) -- 42 Muganu et al. (2013) --/--- 51 Wheeler et al. (2005) ---

34 Linares Torres et al. (2018) -- 43 Rodriguez-Lovelle et al. (2000a)** --/---

35 Lopes et al. (2011) -- 44 Silvestre et al. (2012) --/---

titre du tableau
No trend
1	Costello (2010b)	=	2	Jordan et al. (2016)	=	3	Wilson et al. (2017)	=
Slightly negative
4	DeVetter et al. (2015)	+(T)/-	12	Karl et al. (2016)**	=/--	20	Ingels et al. (2005)*	-(T)/--
5	Krohn and Ferree (2004)	+(T)/--	13	Smith et al. (2008)	=/-	21	Reynolds et al. (2006)**	-(T)/--
6	Sweet and Schreiner (2010)*	+(T)/--	14	Klodd et al. (2016)	- (T)	22	Ripoche et al. (2011)*	- (T)/--
7	Tourte et al. (2008)	=/-(T)	15	Steenwerth et al. (2016)	- (T)	23	Giese et al. (2016)	-
8	Lopes et al. (2008)	=/--	16	Coniberti et al. (2018a)	- (T)/-	24	Steenwerth et al. (2013)	-
9	Mercenaro et al. (2014)	=/-	17	Monteiro and Lopes (2007)	- (T)/-	25	Vrsic et al. (2011)	-
10	Pérez-Álvarez et al. (2015b)	=/-	18	Muscas et al. (2017)*	- (T)/-	26	Pérez et al. (2018)	-/--
11	Trigo-Córdoba et al. (2015)	=/-	19	Tomaz et al. (2015)	- (T)/-
Negative
27	Rodriguez-Lovelle et al. (2000b)	+(T)/---	36	Palliotti et al. (2007)	--	45	Coletta et al. (2013)	---
28	Delpuech and Metay (2018)*	=/--	37	Pou et al. (2011)*	--	46	Coniberti et al. (2017)	---
29	Reeve et al. (2016)	-/---	38	Valdés-Gómez et al. (2011)	--	47	Gontier et al. (2014)	---
30	Coniberti et al. (2018b)	--	39	Caspari et al. (1997)	--/---	48	Hatch et al. (2011)	---
31	De Pascali et al. (2014)	--	40	Guilpart et al. (2017)	--/---	49	Olmstead et al. (2012)	---
32	Giese et al. (2015)	--	41	Mattii et al. (2005)	--/---	50	Toci et al. (2012)	---
33	Hickey et al. (2016)	--	42	Muganu et al. (2013)	--/---	51	Wheeler et al. (2005)	---
34	Linares Torres et al. (2018)	--	43	Rodriguez-Lovelle et al. (2000a)**	--/---
35	Lopes et al. (2011)	--	44	Silvestre et al. (2012)	--/---

= denotes does not affect, no clear trend; – (T)/+(T) denotes reduction trend/general increase; -/+ denotes difference in reduction/increase lower than 20 %; --/++ denotes difference in reduction/increase between 20 and 40 %; ---/+++ denotes difference in reduction/increase higher than 40 %; * denotes differences among treatments in one or more years; ** denotes differences among controls in one or more years.

Table Figure 1. Effect of cover crop use on vine vegetative growth (pruning weight) according to climate and irrigation management.

The most drastic effect was observed in four studies, in which pruning weight reduction was shown to exceed 60 % (Coletta et al., 2013; Gontier et al., 2014; Olmstead et al., 2012; Rodriguez-Lovelle et al., 2000a). The most extreme growth diminution was observed in Olmstead et al. (2012): the cover crop had been established at the time of vineyard planting and the reduction was between 70 and 90 %.

Nine experiments showed reductions in pruning weight of over 40 %, and, quite remarkably, in 5 of them the rootstock was SO4 (Coletta et al., 2013; Coniberti et al., 2018a; Coniberti et al., 2017; Toci et al., 2012; Wheeler et al., 2005). The predominant cover crop species in these experiments was perennial Festuca rubra (Coletta et al., 2013; Gontier et al., 2014; Toci et al., 2012), Festuca arundinacea (Coniberti et al., 2018a; Coniberti et al., 2017; Hatch et al., 2011; Olmstead et al., 2012; Rodriguez-Lovelle et al., 2000a) and Festuca ovina (Coletta et al., 2013; Toci et al., 2012). The average age of these vineyards was 5 years, but it never exceeded 8 years of age, suggesting that under some circumstances the presence of cover crops during the initial years of vineyard's life can be too limiting for proper vineyard development.

Lastly, when the influence of the cover crop on growth was found to be milder (< 20 %) or even not observed at all, most of the experiments relied on irrigation (Giese et al., 2016; Jordan et al., 2016; Klodd et al., 2016; Mercenaro et al., 2014; Monteiro et al., 2008; Monteiro and Lopes, 2007; Steenwerth et al., 2013; Steenwerth et al., 2016; Tourte et al., 2008); only in the minority of cases was irrigation not used (Pérez-Álvarez et al., 2015b; Ripoche et al., 2011; Vrsic et al., 2011). In these cases, cover crops were mainly composed of cereals (Triticum aestivum, Secale cereale and Avena sativa), Lolium and mixtures of grass and legume. The average age of vineyards was around 12 years, which highlights that vineyard age is a key factor in the modulation of vineyard growth response.

Plant water status

Cover crop competition for soil water is a major constraint which needs to be considered when deciding whether to establish a cover crop in areas where a certain amount of water deficit can be expected in summer. In this review, 130 of the selected papers described at least one parameter related to water status: 40 articles measured leaf (25) or stem (15) water potential and, according to the criteria established by Carbonneau and Ojeda (2013), severe water stress was experienced in 5 % of the cases, while moderate to severe levels occurred in 45 % of the cases. Meanwhile, 40 % of the vineyards studied in the reviewed articles experienced mild to moderate water stress, and only 10 % of the vineyards experienced no water stress at all (Table 2).

In most cases, the presence of a cover crop implied a certain increase in water deficit, reaching its maximum around veraison, decreasing again as grape harvest approached, and fading away at the end of the grapevine cycle (Daane et al., 2018; Pou et al., 2011). However, it should be noted that in other cases this point of maximum stress is not so clear (Giese et al., 2015; Hatch et al., 2011; Jordan et al., 2016).Cover-cropped treatments sometimes showed lower leaf water potential at the beginning of the cycle, while the control plots showed the most negative potential values during grape veraison (Steenwerth et al., 2016) or after the start of irrigation (Toci et al., 2012); this may be because water needs in tilled vineyards are greater at the end of the season due to their increased vigour and yield. Rainfall distribution during the grape growing seasons was found to have an extreme impact on plant stress responses; for instance, when rainfall was scarce in spring in one of the three growing seasons compared in Delpuech and Metay (2018) a 60 % cover crop soil coverage led to more negative water potential values than bare soil. Similarly, Pou et al. (2011) only observed significant differences between soil management treatments in the driest years.

Table Table 2. Minimum seasonal values for leaf and stem water potential depending on the cover used – information extracted from the different articles studied.

titre du tableau

N Place Variety Soil management Irrigation Measure Year 1 Year 2 Year 3

Rain (mm) Ψmax (MPa) Sig Rain (mm) Ψmax (MPa) Sig Rain (mm) Ψmax (MPa) Sig

1 Montpellier, France Shiraz Tillage No Ψ_pd - -0.57 End August *

Medicago mix cover -0.64

Spontaneous cover -0.58

2 Nimes,France Shiraz Herbicide No Ψ_pd 493 vc -0.41 End August * 321 vc -0.8 Mid August ns 301 vc -0.51 End August *

Festuca rubra -0.58 -0.89 -0.29

3 Gallargues,France Sauvignon blanc Herbicide - Ψ_pd 650 ay ≈ -0.17 MidJuly ns 650 ay ≈ -0.15 Mid August ns

Festuca arundinacea ≈ -0.16 ≈ -0.18

4 Alentejo,Portugal Tempranillo Tillage Yes Ψ_pd - ≈ -0.6 Mid August * - ≈ -0.4 Mid August *

Spontaneous cover ≈ -0.7 ≈ -0.5

5 Tokaj,Hungary Hárslevelü Tillage - Ψ_pd - ≈ -0.55 - *

Hordeum vulgare ≈ -0.5

Straw ≈ -0.4

6 Alenquer,Portugal Cabernet-Sauvignon Tillage No Ψ_pd 942 y ≈ -0.26 Mid August * 564 y ≈ -0.18 Mid August *

Spontaneous cover ≈ -0.38 ≈ -0.24

60 % Lolium-Festuca, 40 % Trifolium ≈ -0.36 ≈ -0.25

7 Madrid,Spain Shiraz Herbicide Yes Ψ_md 142 y -1.5 Mid August *

Bromus hordeaceus -1.25

Secale cereale -1.4

8 Sacramento County,USA Merlot Tillage Yes Ψ_md - -1.11 July *

Hordeum vulgare, Avena sativa -1.08

Green manure -1.16

Anual clover mix -1.22

California native perennial grass -1.14

9 Fresno County,USA Barbera Tillage Yes - - ≈ -0.92 August ns - ≈ -1.94 August ns

Nassella cernua ≈ -0.92 ≈ -1.72

10 Califronia,USA Cabernet-Sauvignon Tillage No Ψ_md - ≈ -1.0 Mid August ns - ≈ -1.1 Mid August ns

50 % Bromus carinatus, 50 % Elymus glaucus ≈ -0.9 ≈ -1.0

11 Bairrada,Portugal Fernão Pires Tillage No Ψ_pd 137 vc ≈ -0.38 Mid July ns 108 vc ≈ -0.55 August ns

Spontaneous cover ≈ -0.38 ≈ -0.55

12 Tekigdar,Turkey Cabernet-Sauvignon Tillage - Ψ_pd 175 vc ≈ -0.40 August ns

Resilent cover ≈ -0.52

13 Canelones,Uruguay Tannat F. arundinacea-(Herbicide) Yes Ψ_md 668 cv ≈ -1.0 Mid May - 1019 cv ≈ -0.6 Mid May - 1323 cv ≈ -0.8 Mid May -

F. arundinacea - (F. arundinacea) ≈ -1.2 ≈ -0.9 ≈ -0.8

14 Virginia County,USA Cabernet-Sauvignon F. arundinacea, Dactylis glomerata-(Herbicide) Yes Ψ_md 721 cv ≈ -0.65 Mid August ns

Row F. arundinacea, D. glomerata - (F. rubra) ≈ -0.75

15 Salento,Italy Negroamaro Tillage Yes Ψ_md - -1.54 Early August *

F. rubra + F. ovina + Trifolium subterraneum -1.35

16 New York County,USA Cabernet franc F. arundinacea - (Tillage) No Ψ_md 597 -0.85 Early August * 654 -0.29 Mid August *

F. arundinacea - (Herbicide) -1.05 -0.26

F. arundinacea - (Native vegetation) -0.87 -0.28

F. arundinacea - (T. repens) -0.91 -0.28

17 Ourense,Spain Mencía Tillage No Ψ_md 313 cv ≈ -0.6 Early September * 163 cv ≈ -1.0 Early September * 185 cv ≈ -1.0 Early September *

Native vegetation ≈ -1.0 ≈ -1.15 ≈ -1.0

Lolium perenne ≈ -0.9 ≈ -0.95 ≈ -0.7

T. subterraneum ≈ -0.9 ≈ -0.8 ≈ -0.6

18 Montevideo,Uruguay Tannat F. arundinacea - (Herbicide) Yes Ψ_md 650 ay ≈ -1 End January - 650 ay ≈ -0.6 Mid January -

F. arundinacea - (F. arundinacea) ≈ -1.2 ≈ -0.9

19 New York County,USA Cabernet franc Spontaneous vegetation - (Tillage) No Ψ_md 526 cv ≈ -0.5 Mid August ns 450 cv ≈ -0.6 August ns 350 cv ≈ -1.1 Early September ns

Spontaneous vegetation -(Fagopyrum esculentum) ≈ -0.7 ≈ -0.8 ≈ -1.2

Spontaneous vegetation - (Lolium multiflorum) ≈ -0.7 ≈ -1.0 ≈ -1.25

Spontaneous vegetation -(Brassica rapa var. Rapa) ≈ -0.6 ≈ -0.9 ≈ -1.2

20 Oregon County,USA Pinot noir Tillage No Ψ_md 356 cv -0.89 Mid September -

F. rubra -0.77

1: Kazakou et al. (2016); 2: Delpuech and Metay (2018); 3: Celette et al. (2005); 4; Lopes et al. (2011); 5: Judit et al. (2011); 6: Lopes et al. (2008); 7: Linares Torres et al. (2018); 8: Ingels et al. (2005); 9: Costello (2010b); 10: Daane et al. (2018); 11: Cruz et al. (2012); 12: Bahar and Semih Yaşain (2010); 13: Coniberti et al. (2018a); 14: Hatch et al. (2011); 15: Toci et al. (2012); 16: Karl et al. (2016); 17: Trigo-Córdoba et al. (2015); 18: Coniberti et al. (2017); 19: Centinari et al. (2016); 20: Reeve et al. (2016). () denotes under-vine soil management; Ψpd denotes predawn; Ψmd denotes middawn; * denotes significant differences; ns = no significant differences; vc = rainfall during the vine cycle (April-October); y = rainfall in a year; ay = average rainfall in a year.

Apart from the above-described changes in plant water status, which reduce water availability for vines (due to cover crop transpiration), the installation of cover crops can affect water status through other processes that also need to be considered, particularly increased water infiltration or reduced evaporation losses. Regarding the former, Celette and Gary (2013) showed that cover cropping successfully increases the infiltration of water into soil in Montpellier (France), whereas in terms of the latter, some authors have also reported a decrease in soil evaporation at the end of the growing cycle (Steenwerth et al., 2016). Nevertheless, the potential increase in water availability that these two factors cause does not usually compensate for cover crop transpiration. In Celette and Gary (2013), although the presence of the cover crop was shown to improve winter soil water refilling, cover crop transpiration in spring led to similar water availability of grapevine compared to the control plot in the years with moderate water stress, whereas in the drier years it caused higher deficit from budbreak to flowering. As regards the reduction in transpiration, Klodd et al. (2016) observed that, if continuously mowed, a cover crop of F. arundinacea resulted in similar soil water content values than tilled soil, whereas when not mown, soil evapotranspiration increased by about 35–40 %, in both a temperate region (Virginia, USA) and a humid region (Bologna, Italy) (Centinari et al., 2013).

Lastly, cover crop and vine competition for soil water can to a certain extent be compensated for by the different rooting depths of cover crops and vines (Hatch et al., 2011); the compensatory growth of the grapevine root system occurs when a cover crop is established, forcing the vine roots to explore deeper soil horizons (Celette et al., 2008).

Pest and disease incidence

The increase in the biodiversity of flora in the vineyard that can result from the introduction of a cover crop can increase the diversity of insects and indirectly improve the balance between insects and vineyards. Likewise, cover crop usually has the effect of reducing vine vegetative growth, and this can contribute to improved aeration in the vineyard and with it a lower incidence of fungal diseases. In general terms, pest populations in vineyards did not increase in the presence of cover crops in 95 % of the cases considered (whereas 45 % = no changes, and 50 % = decrease; Table 3). Only occasionally, at some specific moments, did Epiphyas postvittana and some homopters show an increase in population when cover crops were used.

The positive impact of cover crops on decreasing pest population is especially clear in the case of Cicadellidae. The pest reduction effect is mainly due to an increased presence of parasitoids of genus Anagrus (Daane et al., 2018; Nicholls et al., 2008). This increase in the population of Anagrus population was not observed in Nicholls et al. (2000) and, as a consequence, Erythroneura populations remained unaltered.

Table Table 3. Main characteristics and results of the impact of cover crops on vineyard pests.

titre du tableau

N Place Variety Soil management Cover type Climate Duration Cicadelidae Spiders Mites Thrips Others

1 Villenave d' Ornon, France Merlot Bared soil*/Spontaneous vegetation SV M 2 - PE - PE, NE = NE Phalangium opilio

2 Virginia, USA Several Tillage*/Spontaneous vegetation TC/SV M 5 = PE Vitacea polistiformis

3 Cerdeña,Italy Carignano Tillage*/ Medicago polymorpha, Trifolium yanninicum/ Dactylis glomerata, Lolium rigidum TC/L/GL W 3 -/= PE Planoccocus ficus

4 Northern Dalmatia,Croatia - Tillage*/Spontaneous vegetation TC/SV M 1 = - Coleoptera

5 Modena,Italy Salamino Tillage*/ Lobularia maritima/ Phacelia tanacetifolia / Fagopyrum esculentum/ Vicia faba/ Vicia villosa, Avena sativa TC/O/O/O/L/GL M 3 + NE(D) +/= PE Homoptera

6 California,USA Cabernet-Sauvignon Tillage*/ Elymus glaucus, Hordeum brachyantherum, Bromus carinatus TC/G W 3 - PE -

7 California,USA Chardonnay Tillage*/ Helianthus annuus,Fagopyrum esculentum TC/O W 2 - PE - PE + NE(D) Coccinelidae, Chrysoperla

8 Marche,Italy Several Tillage*/ Spontaneous vegetation TC/SV M 2 = PE Disease vectors

9 New South Wales,Australia Chardonnay Tillage, Spontaneous vegetation*/ Brassica juncea/ Borago officinalis/ Coriandrum sativum/ F. esculentum/ L.maritima TC, SV/O/O/O/O/O W 1 +/= PE Epiphyas postvittana

10 California,USA Zinfandel Tillage, Spontaneous vegetation*/ B. carinatus TC, SV/G W 2

11 California,USA Cabernet-Sauvignon P. tanacetifolia, Ammi majus, Daucus carota W 2 = PE + NE

12 Marlborough,New Zealand - Spontaneous vegetation*/ V. faba SVC/L M 2 - PE Hemiandrus sp

13 California,USA H.annuus, F. esculentum/Flower island O/O W 2 - PE = NE Coccinelidae, Syrphidae

14 California,USA Zinfandel Tillage*/ Medicago sativa, A. sativa TC/GL W 2 = PE

titre du tableau
N	Place	Variety	Soil management	Cover type	Climate	Duration	Cicadelidae	Spiders	Mites	Thrips	Others
1	Villenave d' Ornon, France	Merlot	Bared soil*/Spontaneous vegetation	SV	M	2	-	PE			-	PE, NE			=	NE	Phalangium opilio
2	Virginia, USA	Several	Tillage*/Spontaneous vegetation	TC/SV	M	5									=	PE	Vitacea polistiformis
3	Cerdeña,Italy	Carignano	Tillage*/ Medicago polymorpha, Trifolium yanninicum/ Dactylis glomerata, Lolium rigidum	TC/L/GL	W	3									-/=	PE	Planoccocus ficus
4	Northern Dalmatia,Croatia	-	Tillage*/Spontaneous vegetation	TC/SV	M	1			=						-		Coleoptera
5	Modena,Italy	Salamino	Tillage*/ Lobularia maritima/ Phacelia tanacetifolia / Fagopyrum esculentum/ Vicia faba/ Vicia villosa, Avena sativa	TC/O/O/O/L/GL	M	3					+	NE(D)			+/=	PE	Homoptera
6	California,USA	Cabernet-Sauvignon	Tillage*/ Elymus glaucus, Hordeum brachyantherum, Bromus carinatus	TC/G	W	3	-	PE	-
7	California,USA	Chardonnay	Tillage*/ Helianthus annuus,Fagopyrum esculentum	TC/O	W	2	-	PE					-	PE	+	NE(D)	Coccinelidae, Chrysoperla
8	Marche,Italy	Several	Tillage*/ Spontaneous vegetation	TC/SV	M	2									=	PE	Disease vectors
9	New South Wales,Australia	Chardonnay	Tillage, Spontaneous vegetation*/ Brassica juncea/ Borago officinalis/ Coriandrum sativum/ F. esculentum/ L.maritima	TC, SV/O/O/O/O/O	W	1									+/=	PE	Epiphyas postvittana
10	California,USA	Zinfandel	Tillage, Spontaneous vegetation*/ B. carinatus	TC, SV/G	W	2
11	California,USA	Cabernet-Sauvignon	P. tanacetifolia, Ammi majus, Daucus carota		W	2	=	PE	+	NE
12	Marlborough,New Zealand	-	Spontaneous vegetation*/ V. faba	SVC/L	M	2									-	PE	Hemiandrus sp
13	California,USA		H.annuus, F. esculentum/Flower island	O/O	W	2	-	PE							=	NE	Coccinelidae, Syrphidae
14	California,USA	Zinfandel	Tillage*/ Medicago sativa, A. sativa	TC/GL	W	2					=	PE

1: Vogelweith and Thiéry (2017); 2: Rijal et al. (2014); 3: Muscas et al. (2017); 4: Franin et al. (2016); 5: Burgio et al. (2016); 6: Daane et al. (2018); 7: Nicholls et al. (2000); 8: Minuz et al. (2013); 9: Begum et al. (2006); 10: Sanguankeo and León (2011); 11: Wilson et al. (2017); 12: Nboyine et al. (2018); 13: Nicholls et al. (2008); 14: Karban et al. (1997). N = number-author reference; Duration: in years from the beginning of the experiment; C = cold climate (average T > 12 ºC); M = mild climate (average T 12-15 ºC); W = warm climate (average T < 15 ºC); *Control management; Cover type: CT = tillage control; G = grass; GL = grass+legume; L = legume; SV = spontaneous vegetation; O = other cover crop group; PE = pest; NE = pest natural enemy; (D) = predator of pests. Symbols: = denotes does not affect; - denotes negative effect compared to the control; + denotes positive effect compared to the control.

The influence of cover crop on grapevine diseases has been mainly studied for powdery mildew (Erysiphe necator), botrytis (Botrytis cinerea), downy mildew (Uncinula necator), black foot disease (Ilyonectria liriodendri) and grape black rot (Guignardia bidwellii). In 12 out of 18 evaluated situations (67 %), the presence of cover crops reduced disease incidence to a certain extent (Table 4).

Table Table 4. Main characteristics and results of the impact of cover crops on grapevine diseases.

titre du tableau

N Place Variety Soil management Cover type Climate Duration Powderymildew Downy mildew Botrytis Black rot Black foot Ilyonectria liriodendri

1 Villenave d' Ornon,France Merlot Bared soil*/Spontaneous vegetation C/SV M 2 = = =

2 Sourthen,Uruguay Tannat Row Festuca arundinacea*/Full cover of F. arundinacea GC/G M 3 -

3 Navarra,Spain Malvasia/Tempranillo¹ Bared soil* /Sinapis alba C/ O M 2 -

4 Blenheim,New Zealand Chardonnay Control*/ Phacelia tanacetifolia/ Lolium perenne C/O/G M 1 -

5 Montpellier,France Aranel Herbicide*/F. arundinacea, L. perenne CH/G M 4 -

6 Madrid,Spain Shiraz Tillage/ Herbicide/ Spontaneous vegetation CT/CH/SV M 3

7 Sourthen,Uruguay Tannat Row F. arundinacea*/Full cover of F. arundinacea GC/G W 2 -

8 Montpellier, France Aranel Herbicide*/ F. arundinacea, Perennial ryegrass/ Hordeum vulgare CH/GR M 5 -/=

9 Bairrada,Portugal Fernão Pires Spontaneous vegetation*/ Tillage CSV/T M 2 -/=

10 Sourthen,Uruguay Tannat Row F. rubra*/Full cover of F. rubra GC/G W 3 -

11 Sourthen,Uruguay Tannat Row F. arundinacea*/Full cover of F. arundinacea GC/G W 3 -

12 Montpellier,France Shiraz Tillage*/ Medicago truncatula, M. rigidula, M. polymorpha TC/L M 3 -/= -/=

13 British Columbia,Canada Exotic grass: F. trachyphylla, Agropyron cristatum, F. rubra, L. perenne/ Exotic grass: Lotus corniculatus, M. lupulina, Trifolium repens/ Native grass: Bouteloua dactyloides, F. idahoensis, Pseudoroegneria spicata, Boteloua gracilis/ Native grass: Nepeta racemosa, Origanum vulgare, Artemisia frigida, Achillea millefolium, Heterotheca villosa , Erigonium neveum, Erigeron filifolius G/GL/G/O GH 1 -

14 Tokaj,Hungary Hárslevelü Tillage*/Hordeum vulgare CT/G C 4 +

15 Ohio, USA Seyval blanc Bared soil*/ Festuca arundinacea/ Mazus japonicus albus/ Mentha pulegium/ Thymus serpyllum minus/ T. fragiferum/ Veronica prostratum/ L. perenne (75%), F. rubra (25%) C/G/O/O/O/L/O/G GH 1 =

titre du tableau
N	Place	Variety	Soil management	Cover type	Climate	Duration	Powderymildew	Downy mildew	Botrytis	Black rot	Black foot	Ilyonectria liriodendri
1	Villenave d' Ornon,France	Merlot	Bared soil*/Spontaneous vegetation	C/SV	M	2	=	=		=
2	Sourthen,Uruguay	Tannat	Row Festuca arundinacea*/Full cover of F. arundinacea	GC/G	M	3			-
3	Navarra,Spain	Malvasia/Tempranillo¹	Bared soil* /Sinapis alba	C/ O	M	2					-
4	Blenheim,New Zealand	Chardonnay	Control*/ Phacelia tanacetifolia/ Lolium perenne	C/O/G	M	1			-
5	Montpellier,France	Aranel	Herbicide*/F. arundinacea, L. perenne	CH/G	M	4			-
6	Madrid,Spain	Shiraz	Tillage/ Herbicide/ Spontaneous vegetation	CT/CH/SV	M	3
7	Sourthen,Uruguay	Tannat	Row F. arundinacea*/Full cover of F. arundinacea	GC/G	W	2			-
8	Montpellier, France	Aranel	Herbicide*/ F. arundinacea, Perennial ryegrass/ Hordeum vulgare	CH/GR	M	5	-/=
9	Bairrada,Portugal	Fernão Pires	Spontaneous vegetation*/ Tillage	CSV/T	M	2			-/=
10	Sourthen,Uruguay	Tannat	Row F. rubra*/Full cover of F. rubra	GC/G	W	3			-
11	Sourthen,Uruguay	Tannat	Row F. arundinacea*/Full cover of F. arundinacea	GC/G	W	3			-
12	Montpellier,France	Shiraz	Tillage*/ Medicago truncatula, M. rigidula, M. polymorpha	TC/L	M	3	-/=		-/=
13	British Columbia,Canada		Exotic grass: F. trachyphylla, Agropyron cristatum, F. rubra, L. perenne/ Exotic grass: Lotus corniculatus, M. lupulina, Trifolium repens/ Native grass: Bouteloua dactyloides, F. idahoensis, Pseudoroegneria spicata, Boteloua gracilis/ Native grass: Nepeta racemosa, Origanum vulgare, Artemisia frigida, Achillea millefolium, Heterotheca villosa , Erigonium neveum, Erigeron filifolius	G/GL/G/O	GH	1						-
14	Tokaj,Hungary	Hárslevelü	Tillage*/Hordeum vulgare	CT/G	C	4			+
15	Ohio, USA	Seyval blanc	Bared soil*/ Festuca arundinacea/ Mazus japonicus albus/ Mentha pulegium/ Thymus serpyllum minus/ T. fragiferum/ Veronica prostratum/ L. perenne (75%), F. rubra (25%)	C/G/O/O/O/L/O/G	GH	1			=

¹Nursery planting material 1: Vogelweith and Thiéry (2017); 2: Coniberti et al. (2018a); 3: Berlanas et al. (2018); 4: Jacometti et al. (2007); 5: Valdés-Gómez et al. (2008); 6: Cordero-Bueso et al. (2011); 7: Coniberti et al. (2017); 8: Valdés-Gómez et al. (2011); 9: Cruz et al. (2012); 10: Coniberti et al. (2018b); 11: Coniberti et al. (2018c); 12: Guilpart et al. (2017); 13: Vukicevich et al. (2018); 14: Judit et al. (2011); 15: Krohn and Ferree (2004). N = number-author reference; Duration, in years from the beginning of the experiment; C = cold climate (average T > 12 ºC); M = mild climate (average T 12-15 ºC); W = warm climate (average T < 15 ºC); Cover type: GH = green house; C = control bared soil; CT = control tillage; CH = control herbicide; SV = spontaneous vegetation; G = grass; GL = grass+legume; L = legume; O = other crop group. Symbols: = denotes does not affect; - donates negative effect compared to the control; + donates positive effect compared to the control.

The establishment of cover crops was found to reduce the incidence of powdery mildew in 2 out of 3 reviewed articles; no increase has ever been observed. In detail, Valdés-Gómez et al. (2011) compared the incidence of powdery mildew on two cover-cropped vineyards (perennial vs. annual) and two herbicide-treated control plots (fertilised and irrigated vs. not fertilised and not irrigated) in Montpellier. They observed that the powdery mildew incidence was higher in the fertilised and irrigated bare soils, but was slightly reduced in bare soils without fertilisation and irrigation practices. Both cover crop treatments showed a relevant decrease in disease incidence, being more significant in the case of a perennial cover crop in its second year of application. The differences among treatments were due to higher vegetative growth (greater number of leaves per shoot) when the cover crop competition was absent or the fertilisation rate increased. Conversely, Vogelweith and Thiéry (2017) did not observe any differences in Bordeaux (France) for powdery mildew incidence when vineyards with a spontaneous cover crop or bare soils were compared.

The evaluation of botrytis incidence on cover-cropped vineyards resulted in no change or in a reduction of this disease in 80 % of the studied cases. In a single experiment in the Tokaj wine region, where Botrytis cinerea is used for the production of its famous sweet wines (and thus known as noble rot), the noble-rotted berries in the bunches from plots with a barley cover crop were reported to have increased by 18 % (Judit et al., 2011). In France, vines with cover crop showed a reduced shoot growth, and thus a decrease in botrytis incidence (Valdés-Gómez et al., 2008). The establishment of under-trellis grass cover crops in vineyards in a humid region in Uruguay also resulted in a reduction in both the incidence and the severity of this disease (Coniberti et al., 2018a). The same authors observed that the extend of disease reduction depends more on the presence/ absence of the cover crop than on the planting density (0.8 m x 2.8 m vs. 1.5 m x 2.8 m) (Coniberti et al., 2018c). Likewise, Jacometti et al. (2007) in New Zealand confirmed that the incidence of botrytis was higher in bare soils compared to mulched plots with mowed or tilled cover crops. This is due to the increase in soil moisture and a higher rate of soil biological activity, increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering and harvest. Between the two studied cover crops, the presence of B. cinerea in Phacelia tanacetifolia cover cropped vineyards tended to be higher than in Lolium perenne, likely due to the reduced competition of soil biota with the fungus. As already mentioned, in some experiments no differences in botrytis incidence associated with the presence of cover crops were found. For instance, in Portugal, no changes were observed between spontaneous cover and till treatments (Cruz et al., 2012). Lastly, in an experiment performed in a greenhouse to compare different cover crops, no differences were found in fungus incidence on the cover crop species in most cases (Krohn and Ferree, 2004).

A study conducted in the South of France by Guilpart et al. (2017) concluded that reduced plant growth had a direct effect on reducing grapevine susceptibility to powdery mildew and botrytis, and that it was directly linked to the reduced plant growth by water stress at flowering in the same year. However, grapevine yield (berry number per bunch and bud fertility) was closely linked to water potential at flowering in the previous year. Thus, appropriate management of cover crops could have a positive impact by reducing fungal diseases based on the climatic variability of the growing season.

The impact of cover crops on downy mildew (P. viticola) incidence on vines has been reported in a single study, in which no differences were detected between treatments (Vogelweith and Thiéry, 2017). The same study revealed that the presence of cover crops did not affect the incidence of black rot (G. bidwellii) either. Moreover, some cover crops have been found to control soil-borne fungal diseases; for instance, Sinapis alba biomass residues incorporated into the soil have shown potential for improving control of black foot disease in nursery planting material (Berlanas et al., 2018). Under greenhouse experimental conditions on soils from different types of groundcover management, a reduction in Ilyonectria liriodendra was observed with cover crop. It seems that the presence of cover crops alters the root-associated fungal communities of soil biota, thus increasing the amount of plant-protective mycoparasites, which could explain the observed reduction in black foot disease incidence (Vukicevich et al., 2018).

Yield

Another aspect that needs to be examined when considering the appropriateness of installing cover crops is their impact on yield. As a general rule, it is assumed that cover crops compete with vines for soil resources (water and nutrients; Gómez, 2017), resulting in a decrease in yield. The analysis of the published papers is mostly in line with this general assumption, but there are some exceptions.

Sixty-eight articles analysed the effect of cover crops on vineyard yield (Table 5). In 16 % of these articles, the presence of cover crops was linked to a 20 to 40 % increase in yield compared to control plots; however, this percentage was outnumbered by articles with results showing that cover crops caused no change (28 %) or a decrease in yield (56 %). Among the latter, 26 articles (38 % of total cases) reported a moderate (< 20 %) reduction in yield, whereas in the remaining 12 papers (17 %) yield loss was > 20 % when cover crops were established.

Table Table 5. Cover crop impact on grape yield compared to tilled and inter-row herbicide-treated control plots.

titre du tableau

Higher, slightly higher

1 Messiga et al. (2016) ++ 5 Fourie (2011) =/++ 9 Marques et al. (2018) -(T)/+++

2 Fourie et al. (2007b)* ++ 6 Steenwerth et al. (2013)*** =/+ 10 Ovalle et al. (2010)* -/+

3 Nboyine et al. (2018) + 7 Steenwerth et al. (2016)* =/+ 11 Ripoche et al. (2011)* -/+

4 Susaj et al. (2013)*** + 8 Steinmaus et al. (2008) =/+

No trend

12 Bettoni et al. (2016) = 19 Ingels et al. (2005) = 26 Rodriguez-Lovelle et al. (2000b)* =

13 Coniberti et al. (2018a) = 20 Lopes et al. (2008) = 27 Smith et al. (2008) =

14 Costello (2010a)* = 21 Mercenaro et al. (2014) = 28 Sweet and Schreiner (2010) =

15 DeVetter et al. (2015) = 22 Monteiro and Lopes (2007) = 29 Tourte et al. (2008) =

16 Donkó et al. (2017) = 23 Pérez-Álvarez et al. (2013) = 30 Wolff et al. (2018) =

17 Giese et al. (2015) = 24 Pérez-Álvarez et al. (2015a) =

18 Giese et al. (2016) = 25 Pérez-Álvarez et al. (2015b) =

Slightly lower

31 Jordan et al. (2016) =/-(T) 40 Tomaz et al. (2015) -(T)/- 49 Klodd et al. (2016) -

32 Ruiz-Colmenero et al. (2011) =/- 41 Coniberti et al. (2017) -(T)/- - 50 Linares Torres et al. (2018)* -

33 Muscas et al. (2017)* =/- - 42 Coniberti et al. (2018c) -(T)/- - 51 Lopes et al. (2011) -

34 Reeve et al. (2016) =/- - 43 Karl et al. (2016)** -(T)/- - 52 Pérez-Bermúdez et al. (2016) -

35 Bahar and Semih Yaşain (2010) -(T) 44 Pérez et al. (2018)* -(T)/- - 53 Rodriguez-Lovelle et al. (2000a)* -

36 Marques et al. (2010) -(T) 45 Pou et al. (2011) -(T)/- - 54 Vrsic et al. (2011) -

37 Trigo-Córdoba et al. (2015)* -(T) 46 Varga et al. (2012)** -/= 55 Nicolosi et al. (2016) -/- -

38 Wheeler et al. (2005) -(T) 47 Hickey et al. (2016) - 56 Coletta et al. (2013) - -/ -

39 Reynolds et al. (2006) -(T)/- 48 Judit et al. (2011) -

Lower

57 Cruz et al. (2012) =/- - - 61 Delpuech and Metay (2018)* - - 65 Palliotti et al. (2007) - -/- - -

58 Guilpart et al. (2017) -(T)/- - - 62 Kazakou et al. (2016)* - - 66 Silvestre et al. (2012) - -/- - -

59 Celette et al. (2005) - - 63 Mattii et al. (2005)* - - 67 Gontier et al. (2014) - - -

60 De Pascali et al. (2014) - - 64 Toci et al. (2012) - - 68 Hatch et al. (2011) - - -

titre du tableau
Higher, slightly higher
1	Messiga et al. (2016)	++	5	Fourie (2011)	=/++	9	Marques et al. (2018)	-(T)/+++
2	Fourie et al. (2007b)*	++	6	Steenwerth et al. (2013)***	=/+	10	Ovalle et al. (2010)*	-/+
3	Nboyine et al. (2018)	+	7	Steenwerth et al. (2016)*	=/+	11	Ripoche et al. (2011)*	-/+
4	Susaj et al. (2013)***	+	8	Steinmaus et al. (2008)	=/+
No trend
12	Bettoni et al. (2016)	=	19	Ingels et al. (2005)	=	26	Rodriguez-Lovelle et al. (2000b)*	=
13	Coniberti et al. (2018a)	=	20	Lopes et al. (2008)	=	27	Smith et al. (2008)	=
14	Costello (2010a)*	=	21	Mercenaro et al. (2014)	=	28	Sweet and Schreiner (2010)	=
15	DeVetter et al. (2015)	=	22	Monteiro and Lopes (2007)	=	29	Tourte et al. (2008)	=
16	Donkó et al. (2017)	=	23	Pérez-Álvarez et al. (2013)	=	30	Wolff et al. (2018)	=
17	Giese et al. (2015)	=	24	Pérez-Álvarez et al. (2015a)	=
18	Giese et al. (2016)	=	25	Pérez-Álvarez et al. (2015b)	=
Slightly lower
31	Jordan et al. (2016)	=/-(T)	40	Tomaz et al. (2015)	-(T)/-	49	Klodd et al. (2016)	-
32	Ruiz-Colmenero et al. (2011)	=/-	41	Coniberti et al. (2017)	-(T)/- -	50	Linares Torres et al. (2018)*	-
33	Muscas et al. (2017)*	=/- -	42	Coniberti et al. (2018c)	-(T)/- -	51	Lopes et al. (2011)	-
34	Reeve et al. (2016)	=/- -	43	Karl et al. (2016)**	-(T)/- -	52	Pérez-Bermúdez et al. (2016)	-
35	Bahar and Semih Yaşain (2010)	-(T)	44	Pérez et al. (2018)*	-(T)/- -	53	Rodriguez-Lovelle et al. (2000a)*	-
36	Marques et al. (2010)	-(T)	45	Pou et al. (2011)	-(T)/- -	54	Vrsic et al. (2011)	-
37	Trigo-Córdoba et al. (2015)*	-(T)	46	Varga et al. (2012)**	-/=	55	Nicolosi et al. (2016)	-/- -
38	Wheeler et al. (2005)	-(T)	47	Hickey et al. (2016)	-	56	Coletta et al. (2013)	- -/ -
39	Reynolds et al. (2006)	-(T)/-	48	Judit et al. (2011)	-
Lower
57	Cruz et al. (2012)	=/- - -	61	Delpuech and Metay (2018)*	- -	65	Palliotti et al. (2007)	- -/- - -
58	Guilpart et al. (2017)	-(T)/- - -	62	Kazakou et al. (2016)*	- -	66	Silvestre et al. (2012)	- -/- - -
59	Celette et al. (2005)	- -	63	Mattii et al. (2005)*	- -	67	Gontier et al. (2014)	- - -
60	De Pascali et al. (2014)	- -	64	Toci et al. (2012)	- -	68	Hatch et al. (2011)	- - -

= denotes does not affect, no clear trend; -(T)/+(T) denotes reduction trend/general increase; -/+ denotes difference in reduction/increase lower than 20 %; --/++ denotes difference in reduction/increase between 20 and 40 %; ---/+++ denotes difference in reduction/increase higher than 40 %; * denotes differences among treatments in one or more years; ** denotes differences among controls in one or more years.

In the studies in which yield increased when using a cover crop, the species used were annual, such as A. sativa (Fourie et al., 2007b; Messiga et al., 2016; Steenwerth et al., 2013; Steenwerth et al., 2016; Steinmaus et al., 2008), or legumes like Trifolium sp. (Messiga et al., 2016; Ovalle et al., 2010; Susaj et al., 2013) and Vicia sp. (Fourie and Freitag, 2010; Messiga et al., 2016; Nboyine et al., 2018; Steenwerth et al., 2013, 2016; Steinmaus et al., 2008). Conversely, permanent cover crops of F. rubra (De Pascali et al., 2014; Gontier et al., 2014; Toci et al., 2012) and F. arundinacea (Celette et al., 2005; Hatch et al., 2011; Mattii et al., 2005; Palliotti et al., 2007) led to a decrease in grape yields. In other cases in which grass- and legume-based cover crops were compared, no differences were observed (Ingels et al., 2005; Steinmaus et al., 2008; Trigo-Córdoba et al., 2015), although there were exceptions (Muscas et al., 2017).

The results obtained when comparing spontaneous versus sown cover crops were inconsistent. In some cases, spontaneous cover crops led to a higher grape yield compared to that of sown cover crops (Mercenaro et al., 2014; Tomaz et al., 2017; Trigo-Córdoba et al., 2015), while in other cases the result was the opposite (Pérez et al., 2018; Susaj et al., 2013).

Finally, when comparing yields of vines with cover crops on every inter-row or every second inter-row, a greater decrease in yield was observed when the plant cover took up the whole inter-row soil surface (Reeve et al., 2016; Rodriguez-Lovelle et al., 2000a; Rodriguez-Lovelle et al., 2000b). The application of vineyard soil mulch (straw and sawdust, etc.), was generally found to lead to increased yields compared to living cover crops or bare soils (Fourie, 2011; Susaj et al., 2013; Varga et al., 2012), but not in all studied cases (Wheeler et al., 2005).

The observed grapevine yield increases took place in areas of warm (average Tª above 15 ºC) and mild (average Tª between 12 and 15 ºC) climate. Only one experiment was performed in a cold climate (average Tª below 12 ºC), in which an increase in yield was found (Hatch et al., 2011). The experiments showing increased yields were located in areas like California (USA) (Steenwerth et al., 2013; Steenwerth et al., 2016; Steinmaus et al., 2008), South Africa (Fourie, 2011; Fourie et al., 2007b), New Zealand (Nboyine et al., 2018) or Chile (Ovalle et al., 2010). However, the vineyards that suffered a loss of yield were located in the Mediterranean climate area (France, Italy and Spain), with the exception of a single experiment in Virginia (USA) (Hatch et al., 2011). Although it is difficult to determine the reasons for these geographical differences, they may be related to a combination of plant water deficit and temperature: the higher these two variables, the greater the reduction in yield (Figure 2).

When climate was analysed alongside irrigation practices, it was shown that, in areas of warm climate, almost all the experiments were under irrigation and positive results were only observed when vineyards were irrigated. In the few experiments performed with irrigation in mild climate areas there was no reduction in grape yield (Figure 2).

Table Figure 2. Impact of cover crops on grapevine yield according to climate conditions and irrigation practices.

Unfertilised vineyards never showed increased yields. However, vineyard fertilisation management showed higher or similar grapevine yields in cover cropped vineyards (Table 6).

Table Table 6. Comparison of cover crop impact on grape yield when the vineyard was fertilised or not.

titre du tableau

Fertilised Not fertilised

Positive, slightly positive 31 % (6) 0 %

No trend 42 % (8) 36 % (5)

Slightly negative 21 % (4) 36 % (5)

Negative 5 % (1) 29 % (4)

titre du tableau
	Fertilised	Not fertilised
Positive, slightly positive	31 % (6)	0 %
No trend	42 % (8)	36 % (5)
Slightly negative	21 % (4)	36 % (5)
Negative	5 % (1)	29 % (4)

Some yield trends were also observed regarding rootstock. For instance, the use of SO4 mainly resulted in a relevant yield decrease (Celette et al., 2005; Cruz et al., 2012; De Pascali et al., 2014; Delpuech and Metay, 2018; Palliotti et al., 2007; Toci et al., 2012), while increases occurred in some of the vineyards with 110R and 99R (Fourie, 2011; Marques et al., 2018; Steenwerth et al., 2013; Steenwerth et al., 2016). When we grouped data according to rootstock tolerance to drought (Figure 3), it was possible to confirm that in the presence of cover crops yield only increased with drought tolerant rootstocks (Fercal, 110R, 140Ru, 99R and 779P). With the remaining rootstocks, (of medium resistance, such as 3309C, SO4, 1103P, 41B; or drought-sensitive, such as 101-14, 420A, 5BB, Teleki 5C), yield was observed to decrease in the presence of cover crops (Figure 3).

Table Figure 3. Number of reviewed papers on the impact of cover crops on grapevine yield grouped according to the rootstock resistance to water stress.

Classification of drought tolerance was performed according to the characteristics of the vine rootstocks published in Vivai Cooperativi Rauscedo (2013), grouped as high (Fercal, 110R, 140Ru, 99R, 779P), medium (3309C, SO4, 1103P, 41B) and low tolerance (101-14, 420A, 5BB, Teleki 5C).

Grape composition

When examining the potential impact of cover crops on grape composition, it is important to take into account that it is intrinsically related to vigour, yield and canopy photosynthetic activity, which are all modified by cover crops. In addition, the presence of cover crops can affect berry size (reduced in 35 % of articles), which may also be associated with changes in berry composition.

Details of grape composition are provided in the following sub-sections. In general terms, total soluble solids (TSS) remained unaffected in 68 % of cases (30 out of 44 papers), whereas in 8 cases they showed an increase, and only 4 reported a decrease in TSS content associated with the introduction of a cover crop (Table 7). When an increase in TSS was observed (6 cases), it was mainly associated with a decrease in yield and berry size (4 cases), although in two of the studies no changes in yield or berry size were reported. Conversely, when a decrease in TSS was observed, it was associated with a reduction in yield, indicating that cover crops were the cause of strong weakening of vineyard. Concerning acidity, 90 % of studied articles (29) reported no change in the pH, whereas in 4 of them a decrease was observed, and only one showed a pH increase associated with cover crop installation. Similarly, cover crops did not alter titratable acidity (TA) in the majority of the studies (23 out of 32, 72 %), a certain decrease was observed in 8, and only 3 reported increased TA.

As regards phenolics, anthocyanins were analysed in 8 studies, out of which 3 showed an increase in anthocyanin content and 5 showed no effect. Meanwhile, for total phenolics the effects were more limited: in 4 out of 7 studies the content remained unchanged, while it increased in 2 and decreased in 1 (Table 7). Lastly, in terms of competition for nutrients, yeast assimilable nitrogen (YAN) was one of the grape composition parameters to be mostly affected by the presence of a cover crop, as it only remained unchanged in 39 % of the experiments and decreased in half of them; only 2 out of 18 studies considered it to have increased. The general implications of cover crops for nitrogen nutrition were reviewed in our companion article (Abad et al., 2021).

Table Table 7. Grape juice quality components.

titre du tableau

N Variety Climate Irrigation Fertilisation Duration Yield Berry weight TSS (ºBrix) pH TA YAN Total anthocyanins Total polyphenols

1 Cabernet-Sauvignon W Yes Yes 2 =/- = = = =/+

2 Tempranillo W Yes No 2 - - =/+ = - = =

3 Sauvignon blanc W Yes Yes 10 +/= = -/= +/=

4 Cabernet-Sauvignon W No Yes 3 = = = - + +

5 Manto Negro W Yes 3 - = = = =

6 Pedro Ximénez W No 3 - = + = = =

7 Canaiolo nero/Trebbiano giallo W 2 = = = =/+

8 Merlot W Yes Yes/No 2/3 = = = =

9 Sangiovese W No 2 - - = + +

10 Carignano W Yes 3 - - =/+ +/- +/-

11 Negroamaro W Yes 1 - = = = =

12 Cabernet-Sauvignon W Yes 1 -/= -/= +/= -

13 Tempranillo W Yes 2 =/- =(w)

14 Negroamaro W Yes 1 - = = = = +(w) =(w)

15 Cabernet-Sauvignon W Yes Yes 2 =

16 Mazuelo W Yes Yes 5 = = = = = =/+

17 Chardonnay W Yes 5 = = = = =/-

18 Chardonnay W Yes Yes 12 =/+ -/= = = = =/-/+

19 Pinnot noir C No 2 = = = = =

20 Pinnot noir C 4 =

21 Furmint/ Hárslevelü C 2 = = =

22 Cabernet-Sauvignon C Yes 7 = = = = = -

23 Mencía C 2 +/=(w) =(w)

24 Gewürztraminer C Yes 6 - = - =/- =/+

25 Maréchal Foch C Yes Yes 7 = = = = +

26 Pinot noir C No Yes 3 =/- = = - -

27 Shiraz M No No 2 -

28 Furmint M 3 = = =

29 Aranel M No No 5/7 - = -/+ -

30 Sauvignon blanc M Yes 4 = = - -

31 Tempranillo M Yes No 3 = = = = = =

32 Sangiovese M 3 - + = -

33 Kallmet M No Yes/No 3 - = = =

34 Merlot M Yes Yes 3 = = = = =

35 Leon Millot M Yes 2 + =/+

36 Merlot M 2 - - + = -

37 Mencía M No 3 =/- =/- = = = =(w)

38 Grechetto M No 6 =/-

39 Merlot, Cabernet franc,Sauvignon blanc M No 2 - -

40 Tempranillo M No 1 = = = = =

41 Fernão Pires M No 2 - - - = =

42 Tempranillo M No No 4 = = = =

43 Cabernet-Sauvignon M 1 = = = =

44 Cabermet-Sauvignon M 2 = = + = - -

45 Tempranillo M No 1 = +

46 Tempranillo M No No 3 = = =/-

titre du tableau
N	Variety	Climate	Irrigation	Fertilisation	Duration	Yield	Berry weight	TSS (ºBrix)	pH	TA	YAN	Total anthocyanins	Total polyphenols
1	Cabernet-Sauvignon	W	Yes	Yes	2		=/-	=	=	=		=/+
2	Tempranillo	W	Yes	No	2	-	-	=/+	=	-		=	=
3	Sauvignon blanc	W	Yes	Yes	10	+/=	=	-/=			+/=
4	Cabernet-Sauvignon	W	No	Yes	3	=		=	=	-		+	+
5	Manto Negro	W	Yes		3	-		=	=			=	=
6	Pedro Ximénez	W	No		3	-	=	+	=	=	=
7	Canaiolo nero/Trebbiano giallo	W			2			=	=	=			=/+
8	Merlot	W	Yes	Yes/No	2/3	=		=	=	=
9	Sangiovese	W		No	2	-	-	=	+	+
10	Carignano	W	Yes		3	-	-	=/+				+/-	+/-
11	Negroamaro	W	Yes		1	-	=	=	=	=
12	Cabernet-Sauvignon	W	Yes		1			-/=	-/=	+/=			-
13	Tempranillo	W	Yes		2	=/-						=(w)
14	Negroamaro	W	Yes		1	-	=	=	=	=		+(w)	=(w)
15	Cabernet-Sauvignon	W	Yes	Yes	2						=
16	Mazuelo	W	Yes	Yes	5	=	=	=	=	=		=/+
17	Chardonnay	W	Yes		5	=	=	=	=	=/-
18	Chardonnay	W	Yes	Yes	12	=/+	-/=	=	=	=	=/-/+
19	Pinnot noir	C	No		2	=		=	=	=	=
20	Pinnot noir	C			4			=
21	Furmint/ Hárslevelü	C			2	=		=		=
22	Cabernet-Sauvignon	C		Yes	7	=	=	=	=	=	-
23	Mencía	C			2							+/=(w)	=(w)
24	Gewürztraminer	C	Yes		6	-	=	-	=/-	=/+
25	Maréchal Foch	C	Yes	Yes	7	=	=	=	=	+
26	Pinot noir	C	No	Yes	3	=/-		=	=	-	-
27	Shiraz	M	No	No	2						-
28	Furmint	M			3	=		=		=
29	Aranel	M	No	No	5/7	-	=	-/+			-
30	Sauvignon blanc	M	Yes		4	=	=	-		-
31	Tempranillo	M	Yes	No	3	=	=	=	=	=			=
32	Sangiovese	M			3		-	+	=	-
33	Kallmet	M	No	Yes/No	3	-	=	=		=
34	Merlot	M	Yes	Yes	3	=	=	=	=	=
35	Leon Millot	M		Yes	2	+		=/+
36	Merlot	M			2	-	-	+	=	-
37	Mencía	M	No		3	=/-	=/-	=	=	=		=(w)
38	Grechetto	M	No		6						=/-
39	Merlot, Cabernet franc,Sauvignon blanc	M		No	2	-					-
40	Tempranillo	M	No		1	=	=	=	=	=
41	Fernão Pires	M	No		2	-	-	-	=	=
42	Tempranillo	M	No	No	4	=		=	=	=
43	Cabernet-Sauvignon	M			1	=		=		=		=
44	Cabermet-Sauvignon	M			2	=	=	+	=	-	-
45	Tempranillo	M		No	1	=						+
46	Tempranillo	M	No	No	3	=	=				=/-

1: Lee and Steenwerth (2013); 2: Lopes et al. (2011); 3: Fourie et al. (2007b); 4: Lopes et al. (2008); 5: Pou et al. (2011); 6: Pérez et al. (2018); 7: Muganu et al. (2013); 8: Ingels et al. (2005); 9: Mattii et al. (2005); 10: Muscas et al. (2017); 11: Toci et al. (2012); 12: Nazrala (2008); 13: Silvestre et al. (2012); 14: Coletta et al. (2013); 15: Lee and Steenwerth (2011); 16: Mercenaro et al. (2014);17: Smith et al. (2008); 18: Fourie (2011); 19: Sweet and Schreiner (2010); 20: Gouthu et al. (2012); 21: Donkó et al. (2017); 22: Giese et al. (2015); 23: Bouzas-Cid et al. (2016); 24: Reynolds et al. (2006); 25: DeVetter et al. (2015); 26: Reeve et al. (2016); 27: Kazakou et al. (2016); 28: Varga et al. (2012); 29: Ripoche et al. (2011); 30: Caspari et al. (1997); 31: Pérez-Bermúdez et al. (2016); 32: Ferrini et al. (1996); 33: Susaj et al. (2013); 34: Steenwerth et al. (2016); 35: Messiga et al. (2016); 36: Rodriguez-Lovelle et al. (2000a); 37: Trigo-Córdoba et al. (2015); 38: Palliotti et al. (2007); 39: Rodriguez-Lovelle et al. (2000b); 40: Marques et al. (2010); 41: Cruz et al. (2012); 42: Pérez-Álvarez et al. (2015a); 43: Bahar and Semih Yaşain (2010); 44: Wheeler et al. (2005); 45: Pérez-Álvarez et al. (2013); 46: Pérez-Álvarez et al. (2015b). Duration: in years since the beginning of the experiment; C = cold climate (average T > 12 ºC); M = mild climate (average T 12-15 ºC); W = warm climate (average T < 15 ºC); TSS = total soluble solids, TA = titrable acidity; YAN = Yeast assimilable nitrogen; (w) = measured in wine.

1. Sugar content and acidity

As mentioned above, the basic grape juice parameters TSS, pH and TA did not show any variation in most of the reviewed studies. Such was the case in several Hungarian wine regions in studies which used a spontaneous cover crop and organic mulching (Varga et al., 2012), or spontaneous flowering legumes and grass cover crops in Furmint vineyards (Donkó et al., 2017). Similarly, no differences in grape juice parameters were found in Pinot noir vineyards when spontaneous legume or grass cover crops (monocultures or mixtures) were compared in Oregon (USA) (Sweet and Schreiner, 2010). Another experiment performed in the same region with the same variety showed no changes in these parameters with a 3-year F. rubra cover crop (Gouthu et al., 2012). The same result was observed in Cabernet-Sauvignon in North Carolina (USA) where grassy cover crops were established (Giese et al., 2015). In Iowa (USA), where the annual precipitation can reach 700 mm, no differences in TSS or pH values were detected with a F. rubra cover crop, although TA showed an upward trend with cv. Maréchal Foch (DeVetter et al., 2015). In a trial conducted in a Merlot vineyard in California, no differences in must parameters were found when green manure, annual clover and perennial grass cover crops were used (Ingels et al., 2005). For the same variety and region, similar results were reported with an oat (A. sativa) cover crop, or a legume/ oat cover crop mixture (Steenwerth et al., 2016). The TSS content in Cabernet-Sauvignon grapes was unaffected by the presence of a native perennial grass cover crop, independently of additional irrigation, although higher irrigation levels appeared to increase yields. Native grasses led to increased tartaric acid contents, while bare soils showed higher levels of malic acid (Daane et al., 2018). S. cereale cover crops did not alter TSS and pH values in Chardonnay vineyards in California, and neither did Triticosecale plant covers. However, the use of Triticosecale resulted in grape juices with lower TA (Smith et al., 2008). The presence of a spontaneous cover crop in a Cabernet-Sauvignon vineyard in Turkey did not alter TSS, pH or TA parameters, although veraison onset was brought forward by 4 days (Bahar and Semih Yaşain, 2010). Cabernet-Sauvignon vineyards in Brasil, managed with Raphanus raphanistrum, Avena strigosa, S. cereale, L. perenne and two clover species showed no differences in TSS and pH values (Bettoni et al., 2016). In a trial conducted in a Manto Negro vineyard in Majorca (Spain), no significant differences were found in must parameters when spontaneous and mixtures of grass and legume cover crops were established compared to tilled control plots (Pou et al., 2011). Similar results were found in Valencia, in Tempranillo and Bobal vineyards with legume cover crops that were tilled at flowering and incorporated into the soil (Pérez-Bermúdez et al., 2016). Similarly, a barley cover crop did not alter TSS, pH, TA, tartaric and malic acid content in Tempranillo vineyards in La Rioja (Spain) and neither did T. resupinatu plant covers (Pérez-Álvarez et al., 2015a).

In contrast to the aforementioned studies, others have reported changes in must composition. For example, spontaneous and A. sativa and Vicia sp. mixtures led to increased TSS content in Pedro Ximenez variety in Andalucía (Spain) after 3 years, although the remaining grape composition parameters were unaltered (Pérez et al., 2018). Ripoche et al. (2011) reported a decrease in TSS content in the first year in cv. Aranel vineyards in Montpellier managed with a permanent F. arundinacea cover crop. Another experiment with cv. Tempranillo in Alentejo (Portugal) showed that the presence of a spontaneous cover crop increased TSS in one of the two study years, but decreased TA in both years (Lopes et al., 2011). In a Cabernet-Sauvignon vineyard located in central Portugal, a reduction in TA was observed in the third season in the presence of a spontaneous cover crop and a grass-legume mixture - probably due to a significant reduction in vegetative growth - whereas no significant differences were found for TSS and pH (Lopes et al., 2008). A 10-year spontaneous cover crop study in Fernão Pires vineyards in Portugal showed a reduced TSS content, as pH and TA remained unaltered (Cruz et al., 2012). The presence of natural permanent plant cover in central Italy resulted in an increased TSS content in Canaiolo nero and Trebbiano giallo grape cultivars during ripening; however, TSS was the same as that for control bare soils at the end of the cycle, whereas pH and TA parameters remained unaffected (Muganu et al., 2013). A F. arundinacea (70 %) and L. perenne (30 %) cover crop resulted in a decrease in TSS content in Grechetto grapevines (Palliotti et al., 2007). The use of natural grass, ground cover with T. subterraneum or with F. arundinacea resulted in higher TSS content while pH and TA tended to decrease in Sangiovese vineyards. Moreover, tall fescue gave an earlier harvest date due to the increased TSS (Ferrini et al., 1996). However, the aforementioned cover crops also in Italy showed an increase in pH and TA parameters while TSS content remained unaltered in the same grape variety (Mattii et al., 2005). Reynolds et al. (2006) observed a delayed grape ripening in Gewürztraminer vineyards in Canada due to the presence of Agropyum cristatum and F. ovina mixture cover crop, accompanied by a decrease in TSS, while TA was unaffected. Furthermore, a trial conducted in Leon Millot vineyards in Canada managed using different cover crop mixtures of legume and grass did not show significant differences in TSS, or were slightly higher in some cases, but those differences were still smaller in the second growing season (Messiga et al., 2016). In a vineyard planted with Merlot variety in France, bloom and veraison occurred earlier in F. arundinacea cover-cropped vines, as berries showed no change in pH and had lower TA and higher TSS content compared to untilled plots (Rodriguez-Lovelle et al., 2000a). Higher TSS content and lower TA were detected in Sauvignon blanc grape juices from L. perenne and Cichorium intybus cover cropped vineyards in New Zealand (Caspari et al., 1997).

More examples of changes in those parameters have been reported in Sauvignon blanc vineyards in South Africa, where TSS content increased and acidity decreased in the presence of a cover crop; this effect was more intense when the cover crop was maintained for a longer period of time during the season (Fourie et al., 2007b). In Uruguay, a full F. rubra cover in a Tannat vineyard also resulted in higher TSS content (Coniberti et al., 2018b).

2. Yeast assimilable nitrogen (YAN)

The impact of cover crops on nitrogen nutrition has already been reviewed in Abad et al. (2021). However due to the impact of YAN on must fermentation and wine characteristics (Bell and Henschke, 2005), we present here the results reported in the articles analysed in the systematic review. As a general rule, legume cover crops usually increase soil N content (Fourie et al., 2007c; Messiga et al., 2015; Ovalle et al., 2007; Pérez-Álvarez et al., 2015b; Sulas et al., 2017), but this increment does not always result in a change in N content in grape juice (Sulas et al., 2017). For instance, a legume cover crop did not cause any increase in YAN in Shiraz grapes, probably as a consequence of the water stress in the soil created by the cover crop that limited N fixation and was managed without irrigation (Kazakou et al., 2016). Conversely, Fourie et al. (2007b) observed an increase in N in grape juice of Sauvignon blanc with the use of Ornithopus sativus and Vicia dasycarpa cover crops, but not in the first years of the study. In this same study, the chemical removal of cover crop before budbreak resulted in a clear increase in must N content.

The general trend for grassy cover crops is the opposite of legume cover regarding nitrogen, as the presence of the crop results in competition for this. In this regard, YAN was observed to decrease in the presence of the following types of cover crops: permanent grass in Cabernet-Sauvignon vineyards in North Carolina (Giese et al., 2015), a mixture of F. arundinacea (70 %) and L. perenne (30 %) in Grechetto vineyards located in central Italy (Palliotti et al., 2007), F. arundinacea in Merlot vineyards in Bordeaux (Rodriguez-Lovelle et al., 2000b), and Chicorium intybus var. sativum in Cabernet-Sauvignon vineyards in New Zealand (Wheeler et al., 2005). These differences between YAN in cove vineyard and nake soil sometimes appear during the first years of the cover crop, as reported for F. arundinacea in Montpellier (Ripoche et al., 2011), and then these get smaller, or can remain unnoticed until the cover crop has been established for several years, as reported with H. vulgare in Tempranillo (Pérez-Álvarez et al., 2015a).

In California, YAN in Cabernet-Sauvignon berries was unaffected by cover crop management (a spontaneous cover crop followed by tillage, or a barley cover mowed and then tilled) (Lee and Steenwerth, 2011). However, in Pinot noir in Oregon, differences in YAN were observed depending on whether the cover crop comprised legume, winter annuals or permanent grass and legume cover crops, although the effect of each cover crop also differed depending on the year (Sweet and Schreiner, 2010). Gouthu et al. (2012), focused their study on the amino acid content of Pinot noir berries in the Finger Lakes region, reporting that the ratio of YAN increased with cover cropping (F. rubra); however, the free amino acid content was 40-45 % lower in berries from cover crop treatments compared to that of berries from control plots. In the cold and humid climate of the Finger Lakes region, where excess levels of N can be a problem, this implies that a competitive cover crop can be an appropriate means of alternative managing vineyard soils.

3. Phenolic compound content

There is also a diversity of results in the influence of the presence of a cover crop on phenolic composition of grapes, although the general trend is for observations of an increase in their content associated with yield reductions. For example, an H. vulgare mown cover crop resulted in higher anthocyanin content than tillage management with Cabernet-Sauvignon in California (Lee and Steenwerth, 2013); this could be linked to decreased berry size. In several experiments conducted in Portugal, phenolics generally increased for at least one of the phenolic compounds measured for Cabernet-Sauvignon (Lopes et al., 2008) and Tempranillo (Silvestre et al., 2012; Tomaz et al., 2017), but no changes were reported in other experiments with Tempranillo (Lopes et al., 2011).

Research performed in a cv. Carignano vineyard in the northwest of Italy revealed that only the presence of a Dactilys glomerate cover crop increased anthocyanins, but this was not the case for different permanent grass-legume mixtures (Mercenaro et al., 2014). In central Italy, the presence of a spontaneous cover crop in cv. Canailo nero, resulted in increased total polyphenol content, while identical management did not obtain the same result in cv. Trebbiano Giallo (Muganu et al., 2013). A F. arundinacea (70 %) and L. perenne (39 %) cover crop caused an increase in polyphenols and colour in the Grechetto white wine grape variety in central Italy (Palliotti et al., 2007), whereas cover cropping with a mix made by 20 % F. rubra, 20 % F. ovina and 60 % T. subterraneum decreased the concentration of flavonoids and anthocyanins in southern Italy. In Sardinia the concentration of total polyphenols and anthocyanins in cv. Carginano increased with D. glomerata (80 %) and Lolium rigidum (20 %), while the spontaneous (Bromus hordeaceus, Avena sterilis and Vulpia myuros) and legume mixture (50 % Medicago polymorpha and 50 % Trifolium yanninicum) cover crops showed reduced values compared to tillage (Muscas et al., 2017).

In Spain, native vegetation and L. perenne cover crops increased anthocyanin concentrations to a greater extent than T. subterraneum for cv. Mencía in Galicia (Bouzas-Cid et al., 2016; Trigo-Córdoba et al., 2015). In a trial conducted in La Rioja, an H. vulgare cover crop resulted in higher levels of polyphenols and colour intensity in Tempranillo, whereas this effect was not observed with a T. resupinatum cover crop (Pérez-Álvarez et al., 2015a). In central Spain, no differences were observed in Tempranillo when tillage and Brachypodium distachyon and S. cereale cover crops were compared (Marques et al., 2010). Similarly, in an experiment carried out in Majorca, the use of spontaneous or grass and legume mixture cover crops did not alter the concentration of total phenolics (Pou et al., 2011).

There are also some reports of research carried out in other countries with varying results depending on the experimental conditions. For instance, a spontaneous cover crop led to reduced tannin and flavonol content, while increased amounts of anthocyanins were observed in Cabernet-Sauvignon vineyards in Mendoza, Argentina (Nazrala, 2008). In New Zealand, a C. intibys var. sativum cover crop resulted in an increased anthocyanin content of Cabernet-Sauvignon berries (Wheeler et al., 2005). Phenolic compounds were also increased by the presence of a natural grass cover in Cabernet-Sauvignon musts from Turkish vineyards (Bahar and Semih Yaşain, 2010), although anthocyanin content decreased. Cover crops in Cabernet-Sauvignon vineyards in China increased total phenols, the highest increase being observed for F. arundinacea, followed by T. repens and M. sativa, while soil tillage providing the lowest values (Xi et al., 2010).

4. Aromas

Comparatively little research has evaluated the impacts of using a cover crop on aromatic compounds. As previously highlighted for the other effects on grape composition, it is important to take into account the fact that the reported effects can vary greatly depending on the research conditions, and that they can frequently be an indirect consequence of changes in yield and vegetative growth.

In a commercial Riesling vineyard in the Finger Lakes region, the use of under-vine cover crops of resident vegetation, buckwheat or L. multiflorum resulted in different perceived aroma in wines compared to when herbicide was used, despite vegetative growth or yield having been unaffected (Jordan et al., 2016). A cover crop treatment consisting in a full cover of the vineyard soil with F. rubra increased fruit aroma and overall aroma intensity of cv. Tannat in Uruguay (Coniberti et al., 2018b). Conversely, in Canada, the use of a mixture of A. cristatum and F. ovina resulted in a Gewürztraminer wine with lower quantities of free volatile terpenes, but higher concentrations of potentially volatile terpenes (Reynolds et al., 2006). Meanwhile, no effect was observed in Sauvignon blanc vineyards in South Africa (Fourie et al., 2007b). In New Zealand, a C. intibys cover crop resulted in an increase in ripe fruit aroma (Wheeler et al., 2005), and a higher glycerol content and lower 2,3-butanediol content were reported in wines produced from vines subjected to cover-cropped treatments in Italy (Coletta et al., 2013; De Pascali et al., 2014; Toci et al., 2012). Furthermore, in the Shaanxi Province, north west China, Xi et al. (2011) detected higher levels of volatile components in Cabernet-Sauvignon when using cover crops, especially those comprising M. sativa and F. arundinacea.

5. Yeast populations

It is also possible for cover crops to have an indirect influence on wild yeast populations, which can in turn affect wine characteristics when fermentation is conducted without the inoculation of commercial yeasts. In this regard, Cordero-Bueso et al. (2011) observed changes in the Saccharomyces populations in spontaneous fermentations during three seasons in Syrah, depended on whether the vines were grown in the presence of a cover crop or of bare soil. The authors hypothesised that the presence of a cover crop in vineyards reduces Saccharomyces populations due to a competitive effect on fungi and grape yeasts populations, reducing yeast quantity and biodiversity in the vineyard, mainly when fermentative strains are used.

Conclusions

The present systematic bibliographic review shows that cover crops tend to result in a reduced vineyard vegetative growth, which can commonly be associated with a reduced incidence of the main fungal diseases. Cover crops generally also reduce the incidence of pests, especially Cicadellidae and mite species, as their presence results in an increase in natural enemies.

In general, cover crops result in an increase in water deficit, although this effect is highly variable as it depends on soil and climate characteristics, and on the period of the year in which the covers are active. The increased competition for water that occurs when cover crops are used can be, to some extent, modulated by the fact that cover crops increase water infiltration into the soil, may reduce soil evaporation or can indirectly lead to lower water needs through leaf area and yield reduction.

The impact of cover crop on vineyard yield is relatively variable. In warmer climates, the observed yield reduction is greater, though irrigation practices tend to compensate for these losses. Apart of soil and climate characteristics, rootstock characteristics also appear to influence the effect of cover crops on grape yield: yield was reported to decrease less with increased rootstock tolerance to drought. Berry size is less affected by the presence of cover crops. Similarly, must quality parameters, like TSS or TA tend to stabilise change, whereas anthocyanins and polyphenols are usually the compounds most favoured by using cover crops. Type of cover crop determines the effect on YAN content, which can decrease, except when the cover crop is comprised of legumes, which usually cause an increase that is generally observed once the cover crop has been established for several seasons.

As a final remark, we consider it worth the effort to carry out the intensive work required to perform a systematic review, as it is the best way to minimise the omission of relevant research and biases in the article selection process. Our two companion papers are an example of how such review methodology can be successfully applied to broad agronomic topics on the variety of impacts that can occur when implementing a growing practice.

Acknowledgements

The author would like to thank María Ancín for her contribution to improving the quality of the text. F.J. Abad is beneﬁciary of postgraduate scholarships funded by INIA (FPI-INIA-2016).

Abad

, Hermoso de Mendoza

, Marín

, Orcaray

, Santesteban

L. G.

, 2021. Cover crops in viticulture. A systematic review (1): Implications on soil characteristics and biodiversity in vineyard. OENO One, 55(1), 295–312. https://doi.org/10.20870/oeno-one.2021.55.1.3599.

Bahar

, Semih Yaşain

, 2010. The yield and berry quality under different soil tillage and clusters thinning treatments in grape (Vitis vinifera L.) cv. Cabernet-Sauvignon. African Journal of Agricultural Research, 5(21), 2986–2993..

Begum

, Gurr

G. M.

, Wratten

S. D.

, Hedberg

P. R.

, Nicol

H. I.

, 2006. Using selective food plants to maximize biological control of vineyard pests. Journal of Applied Ecology, 43(3), 547–554. https://doi.org/10.1111/j.1365-2664.2006.01168.x.

Bell

S. J.

, Henschke

P. A.

, 2005. Implications of nitrogen nutrition for grapes, fermentation and wine. Australian Journal of Grape and Wine Research, 11(3), 242–295. https://doi.org/10.1111/j.1755-0238.2005.tb00028.x.

Berlanas

, Andrés-Sodupe

, López-Manzanares

, Maldonado-González

M. M.

, Gramaje

, 2018. Effect of white mustard cover crop residue, soil chemical fumigation and Trichoderma spp. root treatment on black-foot disease control in grapevine. Pest Management Science, 74(12), 2864–2873. https://doi.org/10.1002/ps.5078.

Bettoni

J. C.

, Feldberg

N. P.

, Nava

, da Veiga

, do Prado Wildner

, 2016. Vegetative, productive and qualitative performance of grapevine “Cabernet-Sauvignon” according to the use of winter cover crops. Revista Ceres, 63(4), 538–544. https://doi.org/10.1590/0034-737X201663040015.

Bouzas-Cid

, Portu

, Pérez-Álvarez

E. P.

, Gonzalo-Diago

, Garde-Cerdán

, 2016. Effect of vegetal ground cover crops on wine anthocyanin content. Scientia Horticulturae, 211, 384–390. https://doi.org/10.1016/j.scienta.2016.09.026.

Burgio

, Marchesini

, Reggiani

, Montepaone

, Schiatti

, Sommaggio

, 2016. Habitat management of organic vineyard in Northern Italy: The role of cover plants management on arthropod functional biodiversity. Bulletin of Entomological Research, 106(6), 759–768. https://doi.org/10.1017/S0007485316000493.

Carbonneau

, Ojeda

, 2013. Écophysiologie et Gestion de l'eau en Viticulture. Retrieved from https://www1.montpellier.inra.fr/pechrouge/images/carbonneau_ecophysiologie_fiches2013.pdf.

Caspari

H. W.

, Neal

, Naylor

, 1997. Cover crop management in vineyards to enhance deficit irrigation in a humid climate. Acta Horticulturae (Vol. 449). https://doi.org/10.17660/ActaHortic.1997.449.44.

Celette

, Gary

, 2013. Dynamics of water and nitrogen stress along the grapevine cycle as affected by cover cropping. European Journal of Agronomy, 45, 142–152. https://doi.org/10.1016/j.eja.2012.10.001.

Celette

, Gaudin

, Gary

, 2008. Spatial and temporal changes to the water regime of a Mediterranean vineyard due to the adoption of cover cropping. European Journal of Agronomy, 29(4), 153–162. https://doi.org/10.1016/j.eja.2008.04.007.

Celette

, Wery

, Chantelot

, Celette

, Gary

, 2005. Belowground interactions in a vine (Vitis vinifera L.)-tall fescue (Festuca arundinacea Shreb.) intercropping system: Water relations and growth. Plant and Soil, 276(1–2), 205–217. https://doi.org/10.1007/s11104-005-4415-5.

Centinari

, Filippetti

, Bauerle

, Allegro

, Valentini

, Poni

, 2013. Cover crop water use in relation to vineyard floor management practices. American Journal of Enology and Viticulture, 64(4), 522–526. https://doi.org/10.5344/ajev.2013.13025.

Centinari

, Vanden Heuvel

J. E.

, Goebel

, Smith

M. S.

, Bauerle

T. L.

, 2016. Root-zone management practices impact above and belowground growth in Cabernet Franc grapevines. Australian Journal of Grape and Wine Research, 22(1), 137–148. https://doi.org/10.1111/ajgw.12162.

Coletta

, Trani

, Faccia

, Punzi

, Dipalmo

, Crupi

, … Gambacorta

, 2013. Influence of viticultural practices and winemaking technologies on phenolic composition and sensory characteristics of Negroamaro red wines. International Journal of Food Science and Technology, 48(11), 2215–2227. https://doi.org/10.1111/ijfs.12207.

Coniberti

, Ferrari

, Disegna

, Dellacassa

, Lakso

A. N.

, 2018a. Under-trellis cover crop and deficit irrigation to regulate water availability and enhance Tannat wine sensory attributes in a humid climate. Scientia Horticulturae, 235, 244–252. https://doi.org/10.1016/j.scienta.2018.03.018.

Coniberti

, Ferrari

, Disegna

, Garcia Petillo

, Lakso

A. N.

, 2018b. Under-trellis cover crop and planting density to achieve vine balance in a humid climate. Scientia Horticulturae, 227, 65–74. https://doi.org/10.1016/j.scienta.2017.09.012.

Coniberti

, Ferrari

, Disegna

, García Petillo

, Lakso

A. N.

, 2018c. Complete vineyard floor cover crop to reduce grapevine susceptibility to bunch rot. European Journal of Agronomy, 99, 167–176. https://doi.org/10.1016/j.eja.2018.07.006.

Coniberti

, Ferrari

, Disegna

, Lakso

A. N.

, García Petillo

, 2017. Interactions of under-trellis cover crops and planting density to achieve vine balance in a temperate humid climate. Acta Horticulturae (Vol. 1177). https://doi.org/10.17660/ActaHortic.2017.1177.49.

Cordero-Bueso

, Arroyo

, Serrano

, Valero

, 2011. Influence of different floor management strategies of the vineyard on the natural yeast population associated with grape berries. International Journal of Food Microbiology, 148(1), 23–29. https://doi.org/10.1016/j.ijfoodmicro.2011.04.021.

Costello

M. J.

, 2010a. Grapevine and soil water relations with nodding needlegrass (Nassella cernua), a California native grass, as a cover crop. HortScience, 45(4), 621–627. https://doi.org/10.21273/HORTSCI.45.4.621.

Costello

M. J.

, 2010b. Growth and yield of cultivated grape with native perennial grasses nodding needlegrass or California barley as cover crops. HortScience, 45(1), 154–156. https://doi.org/10.21273/HORTSCI.45.1.154.

Cruz

, Botelho

, Silvestre

, de Castro

, 2012. Soil management: Introduction of tillage in a vineyard with a long-term natural cover. Ciencia E Tecnica Vitivinicola, 27(1), 27–38..

Daane

K. M.

, Hogg

B. N.

, Wilson

, Yokota

G. Y.

, 2018. Native grass ground covers provide multiple ecosystem services in Californian vineyards. Journal of Applied Ecology, 55(5), 2473–2483. https://doi.org/10.1111/1365-2664.13145.

Dardeniz

, Yıldırım

, Gökbayrak

, Akçal

, 2008. Influence of shoot topping on yield and quality of Vitis vinifera L. African Journal of Biotechnology, 7(20), 3628–3631. https://doi.org/10.5897/AJB08.461.

De Pascali

S. A.

, Coletta

, Del Coco

, Basile

, Gambacorta

, Fanizzi

F. P.

, 2014. Viticultural practice and winemaking effects on metabolic profile of Negroamaro. Food Chemistry, 161, 112–119. https://doi.org/10.1016/j.foodchem.2014.03.128.

Delpuech

, Metay

, 2018. Adapting cover crop soil coverage to soil depth to limit competition for water in a Mediterranean vineyard. European Journal of Agronomy, 97, 60–69. https://doi.org/10.1016/j.eja.2018.04.013.

DeVetter

L. W.

, Dilley

C. A.

, Nonnecke

G. R.

, 2015. Mulches reduce weeds, maintain yield, and promote soil quality in a continental-climate vineyard. American Journal of Enology and Viticulture, 66(1), 54–64. https://doi.org/10.5344/ajev.2014.14064.

Donkó

Á.

, Miglécz

, Valkó

, Tóthmérész

, Deák

, Kelemen

, … Drexler

, 2017. Comparison of species-rich cover crop mixtures in the Tokaj wine region (Hungary). Organic Agriculture, 7(2), 133–139. https://doi.org/10.1007/s13165-016-0149-3.

Ferrini

, Mattii

G. B.

, Storchi

, 1996. Effect of various ground covers on berry and must characteristics of “Sangiovese” wine grape in the Brunello di Montalcino area. Acta Horticulturae (Vol. 427)..

Fourie

J. C.

, 2011. Soil management in the breede river valley wine grape region, South Africa. 3. Grapevine performance. South African Journal of Enology and Viticulture, 32(1), 60–70..

Fourie

J. C.

, Freitag

, 2010. Soil management in the Breede River Valley wine grape region, South Africa. 2. Soil temperature. South African Journal of Enology and Viticulture, 31(2), 165–168..

Fourie

J. C.

, Agenbag

G. A.

, Louw

P. J. E.

, 2007a. Cover crop management in a Chardonnay/99 richter vineyard in the coastal region, South Africa. 3. Effect of different cover crops and cover crop management practices on organic matter and macro-nutrient content of a medium-textured soil. South African Journal of Enology and Viticulture, 28(1), 61–68..

Fourie

J. C.

, Agenbag

G. A.

, Louw

P. J. E.

, 2007b. Cover crop management in a Sauvignon blanc/Ramsey vineyard in the Semi-Arid Olifants River Valley, South Africa. 3. effect of different cover crops and cover crop management practices on the organic matter and macro-nutrient contents of a Sandy Soil. South African Journal of Enology and Viticulture, 28(2), 92–100..

Fourie

J. C.

, Louw

P. J. E.

, Agenbag

G. A.

, 2007c. Cover Crop Management in a Sauvignon blanc/Ramsey vineyard in the semi-arid Olifants River Valley, South Africa. 2. Effect of different cover crops and cover crop management practices on grapevine performance. South African Journal of Enology and Viticulture, 28(2), 81–91. https://doi.org/10.21548/28-2-1463.

Franin

, Kuštera

, Šišeta

, 2016. Fauna of ground-dwelling arthropods in vineyards of Zadar County (Croatia) | Fauna prizemnih člankonožaca u vinogradima Zadarske županije (Hrvatska). Poljoprivreda, 22(2), 50–56. https://doi.org/10.18047/poljo.22.2.8.

Giese

G. W.

, Wolf

T. K.

, Velasco-Cruz

, Roberts

, 2016. Cover crop and root pruning effects on the rooting pattern of SO4 rootstock grafted to Cabernet-Sauvignon. American Journal of Enology and Viticulture, 67(1), 105–115. https://doi.org/10.5344/ajev.2015.15066.

Giese

, Wolf

T. K.

, Velasco-Cruz

, Roberts

, Heitman

, 2015. Cover crop and root pruning impacts on vegetative growth, crop yield components, and grape composition of Cabernet-Sauvignon. American Journal of Enology and Viticulture, 66(2), 212–226. https://doi.org/10.5344/ajev.2014.14100.

Gómez

J. A.

, 2017. Sustainability using cover crops in mediterranean tree crops, olives and vines – challenges and current knowledge. Hungarian Geographical Bulletin, 66(1), 13–28. https://doi.org/10.15201/hungeobull.66.1.2.

Gontier

, Caboulet

, Lhoutellier

, 2014. Assessment of the agronomic value of sewage sludge compost applied on wine-growing soils. Acta Horticulturae (Vol. 1018). https://doi.org/10.17660/ActaHortic.2014.1018.26.

Gouthu

, Skinkis

P. A.

, Morre

, Maier

C. S.

, Deluc

L. G.

, 2012. Berry nitrogen status altered by cover cropping: Effects on berry hormone dynamics, growth and amino acid composition of Pinot Noir. Food Chemistry, 135(1), 1–8. https://doi.org/10.1016/j.foodchem.2012.04.019.

Guilpart

, Roux

, Gary

, Metay

, 2017. The trade-off between grape yield and grapevine susceptibility to powdery mildew and grey mould depends on inter-annual variations in water stress. Agricultural and Forest Meteorology, 234–235, 203–211. https://doi.org/10.1016/j.agrformet.2016.12.023.

Hatch

T. A.

, Hickey

C. C.

, Wolf

T. K.

, 2011. Cover crop, rootstock, and root restriction regulate vegetative growth of Cabernet-Sauvignon in a humid environment. American Journal of Enology and Viticulture, 62(3), 298–311. https://doi.org/10.5344/ajev.2011.11001.

Hickey

C. C.

, Hatch

T. A.

, Stallings

, Wolf

T. K.

, 2016. Under-trellis cover crop and rootstock affect growth, yield components, and fruit composition of cabernet sauvignon. American Journal of Enology and Viticulture, 67(3), 281–295. https://doi.org/10.5344/ajev.2016.15079.

Ibañez Pascual

, 2013. Gestión del suelo en viñedo mediante cubiertas vegetales . Incidencia sobre el control del rendimiento y del vigor . Aspectos ecofisiológicos , nutricionales ,. Universidad de La Rioja..

Ingels

C. A.

, Scow

K. M.

, Whisson

D. A.

, Drenovsky

R. E.

, 2005. Effects of cover crops on grapevines, yield, juice composition, soil microbial ecology, and gopher activity. American Journal of Enology and Viticulture, 56(1), 19–29..

Jacometti

M. A.

, Wratten

S. D.

, Walter

, 2007. Enhancing ecosystem services in vineyards: Using cover crops to decrease botrytis bunch rot severity. International Journal of Agricultural Sustainability, 5(4), 305–314. https://doi.org/10.1080/14735903.2007.9684830.

Jordan

L. M.

, Björkman

, Heuvel

J. E. V.

, 2016. Annual under-vine cover crops did not impact vine growth or fruit composition of mature cool-climate “riesling” grapevines. HortTechnology, 26(1), 36–45..

Judit

, Gábor

, Ádám

, Tamàs

, György

, 2011. Comparison of three soil management methods in the Tokaj wine region. Mitteilungen Klosterneuburg, 61(4), 187–195..

Karban

, English-Loeb

, Hougen-Eitzman

, 1997. Mite vaccinations for sustainable management of spider mites in vineyards. Ecological Applications, 7(1), 183–193. https://doi.org/10.1890/1051-0761(1997)007[0183:MVFSMO]2.0.CO;2.

Karl

, Merwin

I. A.

, Brown

M. G.

, Hervieux

R. A.

, Heuvel

J. E. V.

, 2016. Impact of undervine management on vine growth, yield, fruit composition, and wine sensory analyses in cabernet franc. American Journal of Enology and Viticulture, 67(3), 269–280. https://doi.org/10.5344/ajev.2016.15061.

Kazakou

, Fried

, Richarte

, Gimenez

, Violle

, Metay

, 2016. A plant trait-based response-and-effect framework to assess vineyard inter-row soil management. Botany Letters, 163(4), 373–388. https://doi.org/10.1080/23818107.2016.1232205.

Klodd

A. E.

, Eissenstat

D. M.

, Wolf

T. K.

, Centinari

, 2016. Coping with cover crop competition in mature grapevines. Plant Soil, 400, 391–402. https://doi.org/10.1007/s11104-015-2748-2.

Krnic Martinic

, Pieper

, Glatt

, Puljak

, 2019. Definition of a systematic review used in overviews of systematic reviews, meta-epidemiological studies and textbooks. BMC Medical Research Methodology, 19(1), 1–12. https://doi.org/10.1186/s12874-019-0855-0.

Krohn

, Ferree

, 2004. The effects of ornamental ground covers on the growth and fruiting of containerized seyval blanc grapevines. Acta Horticulturae (Vol. 640)..

Lee

, Steenwerth

K. L.

, 2011. Rootstock and vineyard floor management influence on “Cabernet-Sauvignon” grape yeast assimilable nitrogen (YAN). Food Chemistry, 127(3), 926–933. https://doi.org/10.1016/j.foodchem.2011.01.060.

Lee

, Steenwerth

K. L.

, 2013. “Cabernet-Sauvignon” grape anthocyanin increased by soil conservation practices. Scientia Horticulturae, 159, 128–133. https://doi.org/10.1016/j.scienta.2013.05.025.

Linares Torres

, De La Fuente Lloreda

, Junquera Gonzalez

, Lissarrague García-Gutierrez

J. R.

, Baeza Trujillo

, 2018. Effect of soil management strategies on the characteristics of the grapevine root system in irrigated vineyards under semi-arid conditions. Australian Journal of Grape and Wine Research, 24(4), 439–449. https://doi.org/10.1111/ajgw.12359.

Lopes

C. M.

, Monteiro

, Machado

J. P.

, Fernandes

, Araújo

, 2008. Cover cropping in a sloping non-irrigated vineyard: II - Effects on vegetative growth, yield, berry and wine quality of “Cabernet-Sauvignon” grapevines | Enrelvamento em vinha de encosta não regada: II - Efeitos no crescimento vegetativo, produção e quali. Ciencia E Tecnica Vitivinicola, 23(1), 37–43..

Lopes

C. M.

, Santos

T. P.

, Monteiro

, Rodrigues

M. L.

, Costa

J. M.

, Chaves

M. M.

, 2011. Combining cover cropping with deficit irrigation in a Mediterranean low vigor vineyard. Scientia Horticulturae, 129(4), 603–612. https://doi.org/10.1016/j.scienta.2011.04.033.

Marques

F. J. M.

, Pedroso

, Trindade

, Pereira

J. L. S.

, 2018. Impact of vineyard cover cropping on carbon dioxide and nitrous oxide emissions in Portugal. Atmospheric Pollution Research, 9(1), 105–111. https://doi.org/10.1016/j.apr.2017.07.006.

Marques

M. J.

, García-Muñoz

, Muñoz-Organero

, Bienes

, 2010. Soil conservation beneath grass cover in hillside vineyards under mediterranean climatic conditions (MADRID, SPAIN). Land Degradation and Development, 21(2), 122–131. https://doi.org/10.1002/ldr.915.

Mattii

G. B.

, Storchi

, Ferrini

, 2005. Effects of soil management on physiological, vegetative and reproductive characteristics of Sangiovese grapevine. Advances in Horticultural Science, 19(4), 198–205..

Mercenaro

, Nieddu

, Pulina

, Porqueddu

, 2014. Sustainable management of an intercropped Mediterranean vineyard. Agriculture, Ecosystems and Environment, 192, 95–104. https://doi.org/10.1016/j.agee.2014.04.005.

Messiga

A. J.

, Gallant

K. S.

, Sharifi

, Hammermeister

, Fuller

, Tango

, Fillmore

, 2016. Grape yield and quality response to cover crops and amendments in a vineyard in Nova Scotia, Canada. American Journal of Enology and Viticulture, 67(1), 77–85. https://doi.org/10.5344/ajev.2015.15013.

Messiga

A. J.

, Sharifi

, Hammermeister

, Gallant

, Fuller

, Tango

, 2015. Soil quality response to cover crops and amendments in a vineyard in Nova Scotia, Canada. Scientia Horticulturae, 188, 6–14. https://doi.org/10.1016/j.scienta.2015.02.041.

Minuz

R. L.

, Isidoro

, Casavecchia

, Burgio

, Riolo

, 2013. Sex-dispersal differences of four phloem-feeding vectors and their relationship to wild-plant abundance in vineyard agroecosystems. Journal of Economic Entomology, 106(6), 2296–2309. https://doi.org/10.1603/EC13244.

Monteiro

, Lopes

C. M.

, 2007. Influence of cover crop on water use and performance of vineyard in Mediterranean Portugal. Agriculture, Ecosystems and Environment, 121(4), 336–342. https://doi.org/10.1016/j.agee.2006.11.016.

Monteiro

, Lopes

C. M.

, Machado

J. P.

, Fernandes

, Araújo

, Moreira

, 2008. Cover cropping in a sloping, non-irrigated vineyard: I - Effects on weed composition and dynamics | Enrelvamento em vinha de encosta não regada: I - Efeito na composição e dinâmica das infestantes. Ciencia E Tecnica Vitivinicola, 23(1), 29–36..

Muganu

, Paolocci

, Gnisci

, Barnaba

F. E.

, Bellincontro

, Mencarelli

, Grosu

, 2013. Effect of different soil management practices on grapevine growth and on berry quality assessed by NIR-AOTF spectroscopy. Acta Horticulturae (Vol. 978). https://doi.org/10.17660/ActaHortic.2013.978.12.

Muscas

, Cocco

, Mercenaro

, Cabras

, Lentini

, Porqueddu

, Nieddu

, 2017. Effects of vineyard floor cover crops on grapevine vigor, yield, and fruit quality, and the development of the vine mealybug under a Mediterranean climate. Agriculture, Ecosystems and Environment, 237, 203–212. https://doi.org/10.1016/j.agee.2016.12.035.

Nazrala

J. J. B.

, 2008. Influence of the management of the soil and covers in the canopy microclimate of vine, grape and wine composition | Influencia del manejo del suelo y las coberturas vegetales en el microclima de la canopia de la vid, la composición de la uva y el vino. Revista de La Facultad de Ciencias Agrarias, 40(1), 85–104..

Nboyine

J. A.

, Boyer

, Saville

D. J.

, Wratten

S. D.

, 2018. Agroecological management of a soil-dwelling orthopteran pest in vineyards. Insect Science, 25(3), 475–486. https://doi.org/10.1111/1744-7917.12425.

Nicholls

C. I.

, Altieri

M. A.

, Ponti

, 2008. Enhancing plant diversity for improved insect pest management in Northern California organic vineyards. Acta Horticulturae (Vol. 785). https://doi.org/10.17660/ActaHortic.2008.785.32.

Nicholls

C. I.

, Parrella

M. P.

, Altieri

M. A.

, 2000. Reducing the abundance of leafhoppers and thrips in a northern California organic vineyard through maintenance of full season floral diversity with summer cover crops. Agricultural and Forest Entomology, 2(2), 107–113. https://doi.org/10.1046/j.1461-9563.2000.00054.x.

Nicolosi

, Ferlito

, Allegra

, Cicala

, Trovato

, La Malfa

, 2016. Influences of aspect and tillage on two winegrape cultivars on Mount Etna. New Zealand Journal of Crop and Horticultural Science, 44(2), 83–102. https://doi.org/10.1080/01140671.2016.1147472.

Olmstead

, Miller

T. W.

, Bolton

C. S.

, Miles

C. A.

, 2012. Weed control in a newly established organic vineyard. HortTechnology, 22(6), 757–765..

Ovalle

, Del Pozo

, Lavín

, Hirzel

, 2007. Cover crops in vineyards: Performance of annual forage legume mixtures and effects on soil fertility | Cubiertas vegetales en viñedos: Comportamiento de mezclas de leguminosas forrajeras anuales y efectos sobre la fertilidad del suelo. Agricultura Tecnica, 67(4), 384–392..

Ovalle

, del Pozo

, Peoples

M. B.

, Lavín

, 2010. Estimating the contribution of nitrogen from legume cover crops to the nitrogen nutrition of grapevines using a15N dilution technique. Plant and Soil, 334(1), 247–259. https://doi.org/10.1007/s11104-010-0379-1.

Palliotti

, Cartechini

, Silvestroni

, Mattioli

, Petoumenou

, Berrios

J. G.

, 2007. Long-term effects of seeded cover-crop on vegetative characteristics, yield and grape and wine composition of “grechetto” grapevines in central Italy. Acta Horticulturae (Vol. 754)..

Parker

A. K.

, Raw

, Martin

, Haycock

, Sherman

, Trought

M. C. T.

, 2016. Reduced grapevine canopy size post-flowering via mechanical trimming alters ripening and yield of “Pinot noir.” Vitis - Journal of Grapevine Research, 55(1), 1–9. https://doi.org/10.5073/vitis.2016.55.1-9.

Pérez-Álvarez

E. P.

, García-Escudero

, Peregrina

, 2015a. Soil nutrient availability under Cover Crops: Effects on vines, must, and wine in a Tempranillo Vineyard. American Journal of Enology and Viticulture, 66(3), 311–320. https://doi.org/10.5344/ajev.2015.14092.

Pérez-Álvarez

E. P.

, Garde-Cerdán

, Santamaría

, García-Escudero

, Peregrina

, 2015b. Influence of two different cover crops on soil N availability, N nutritional status, and grape yeast-assimilable N (YAN) in a cv. Tempranillo vineyard. Plant and Soil, 390(1–2), 143–156. https://doi.org/10.1007/s11104-015-2387-7.

Pérez-Álvarez

E. P.

, Pérez-Sotés

J. L.

, García-Escudero

, Peregrina

, 2013. Cover Crop Short-Term Effects on Soil NO3 N Availability, Nitrogen Nutritional Status, Yield, and Must Quality in a Calcareous Vineyard of the AOC Rioja, Spain. Communications in Soil Science and Plant Analysis, 44(1–4), 711–721. https://doi.org/10.1080/00103624.2013.748122.

Pérez-Bermúdez

, Olmo

, Gil

, García-Férriz

, Olmo

, Boluda

, Gavidia

, 2016. Cover crops and pruning in Bobal and Tempranillo vineyards have little influence on grapevine nutrition. Scientia Agricola, 73(3), 260–265. https://doi.org/10.1590/0103-9016-2015-0027.

Pérez

P. R.

, Luque

J. M. C.

, Marín

R. S.

, Gutiérrez

J. M. L.

, 2018. Efectos del uso de cubiertas vegetales en viñedo ecológico de la variedad Pedro Ximénez. In E3S Web of Conferences (Vol. 50). https://doi.org/10.1051/e3sconf/20185001008.

Pou

, Gulías

, Moreno

, Tomás

, Medrano

, Cifre

, 2011. Cover cropping in Vitis vinifera L. cv. Manto Negro vineyards under Mediterranean conditions: Effects on plant vigour, yield and grape quality. Journal International Des Sciences de La Vigne et Du Vin, 45(4), 223–234..

Reeve

A. L.

, Skinkis

P. A.

, Vance

A. J.

, Lee

, Tarara

J. M.

, 2016. Vineyard floor management influences “pinot noir” vine growth and productivity more than cluster thinning. HortScience, 51(10), 1233–1244. https://doi.org/10.21273/HORTSCI10998-16.

Reynolds

A. G.

, Parchomchuk

, Berard

, Naylor

A. P.

, Hogue

, 2006. Gewurztraminer grapevines respond to length of water stress duration. International Journal of Fruit Science, 5(4), 75–94. https://doi.org/10.1300/J492v05n04_09.

Rijal

J. P.

, Brewster

C. C.

, Bergh

J. C.

, 2014. Effects of biotic and abiotic factors on grape root borer (Lepidoptera: Sesiidae) infestations in commercial vineyards in Virginia. Environmental Entomology, 43(5), 1198–1208. https://doi.org/10.1603/EN14094.

Ripoche

, Metay

, Celette

, Gary

, 2011. Changing the soil surface management in vineyards: Immediate and delayed effects on the growth and yield of grapevine. Plant and Soil, 339(1), 259–271. https://doi.org/10.1007/s11104-010-0573-1.

Rodriguez-Lovelle

, Soyer

J. P.

, Molot

, 2000a. Incidence of permanent grass cover on grapevine phenological evolution and grape berry ripening. Acta Horticulturae (Vol. 526). https://doi.org/10.17660/ActaHortic.2000.526.24.

Rodriguez-Lovelle

, Soyer

J. P.

, Molot

, 2000b. Nitrogen availability in vineyard soils according to soil management practices. effects on vine. Acta Horticulturae (Vol. 526)..

Ruiz-Colmenero

, Bienes

, Marques

M. J.

, 2011. Soil and water conservation dilemmas associated with the use of green cover in steep vineyards. Soil and Tillage Research, 117, 211–223. https://doi.org/10.1016/j.still.2011.10.004.

Sanguankeo

P. P.

, León

R. G.

, 2011. Weed management practices determine plant and arthropod diversity and seed predation in vineyards. Weed Research, 51(4), 404–412. https://doi.org/10.1111/j.1365-3180.2011.00853.x.

Silvestre

J. C.

, Canas

, Brazão

, Caldeira

, Clímaco

, Duarte

, … Malheiro

A. C.

, 2012. Influence of timing and intensity of deficit irrigation on vine vigour, yield and berry and wine composition of “Tempranillo” in southern Portugal. Acta Horticulturae (Vol. 931)..

Smart

R. E.

, Dick

J. K.

, Gravett

I. M.

, Fisher

B. M.

, 2017. Canopy Management to Improve Grape Yield and Wine Quality - Principles and Practices. South African Journal of Enology & Viticulture, 11(1), 3–17. https://doi.org/10.21548/11-1-2232.

Smith

, Bettiga

, Cahn

, Baumgartner

, Jackson

L. E.

, Bensen

, 2008. Vineyard floor management affects soil, plant nutrition, and grape yield and quality. California Agriculture, 62(4), 184–190. https://doi.org/10.3733/ca.v062n04p184.

100

Steenwerth

K. L.

, Calderón-Orellana

, Hanifin

R. C.

, Storm

, McElrone

A. J.

, 2016. Effects of various vineyard floor management techniques on weed community shifts and grapevine water relations. American Journal of Enology and Viticulture, 67(2), 153–162. https://doi.org/10.5344/ajev.2015.15050.

101

Steenwerth

K. L.

, McElrone

A. J.

, Calderón-Orellana

, Hanifin

R. C.

, Storm

, Collatz

, Manuck

, 2013. Cover crops and tillage in a mature Merlot vineyard show few effects on grapevines. American Journal of Enology and Viticulture, 64(4), 515–521. https://doi.org/10.5344/ajev.2013.12119.

102

Steinmaus

, Elmore

C. L.

, Smith

R. J.

, Donaldson

, Weber

E. A.

, Roncoroni

J. A.

, Miller

P. R. M.

, 2008. Mulched cover crops as an alternative to conventional weed management systems in vineyards. Weed Research, 48(3), 273–281. https://doi.org/10.1111/j.1365-3180.2008.00626.x.

103

Sulas

, Mercenaro

, Campesi

, Nieddu

, 2017. Different cover crops affect nitrogen fluxes in mediterranean vineyard. Agronomy Journal, 109(6), 2579–2585. https://doi.org/10.2134/agronj2017.05.0283.

104

Susaj

, Susaj

, Belegu

, Mustafa

, Dervishi

, Ferraj

, 2013. Effects of different weed management practices on production and quality of wine grape cultivar Kallmet in North-Western Albania. Journal of Food, Agriculture and Environment, 11(1), 379–382..

105

Sweet

R. M.

, Schreiner

R. P.

, 2010. Alleyway cover crops have little infuence on pinot noir grapevines (Vitis vinifera L.) in two western Oregon vineyards. American Journal of Enology and Viticulture, 61(2), 240–252..

106

Toci

A. T.

, Crupi

, Gambacorta

, Dipalmo

, Antonacci

, Coletta

, 2012. Free and bound aroma compounds characterization by GC-MS of Negroamaro wine as affected by soil management. Journal of Mass Spectrometry, 47(9), 1104–1112. https://doi.org/10.1002/jms.3045.

107

Tomaz

, Martinez

J. M. C.

, Pacheco

C. A.

, 2015. Yield and quality responses of “Aragonez” grapevines under deficit irrigation and different soil management practices in a Mediterranean climate. Ciencia e Tecnica Vitivinicola, 30(1), 9–20. https://doi.org/10.1051/ctv/20153001009.

108

Tomaz

, Pacheco

C. A.

, Coleto Martinez

J. M.

, 2017. Influence of cover cropping on water uptake dynamics in an irrigated Mediterranean vineyard. Irrigation and Drainage, 66(3), 387–395. https://doi.org/10.1002/ird.2115.

109

Tourte

, Smith

, Bettiga

, Bensen

, Smith

, Salm

, 2008. Post-emergence herbicides are cost effective for vineyard floor management on the Central Coast. California Agriculture, 62(1), 19–23. https://doi.org/10.3733/ca.v062n01p19.

110

Trigo-Córdoba

, Bouzas-Cid

, Orriols-Fernández

, Díaz-Losada

, Mirás-Avalos

J. M.

, 2015. Influence of cover crop treatments on the performance of a vineyard in a humid region. Spanish Journal of Agricultural Research, 13(4). https://doi.org/10.5424/sjar/2015134-8265.

111

Valdés-Gómez

, Fermaud

, Roudet

, Calonnec

, Gary

, 2008. Grey mould incidence is reduced on grapevines with lower vegetative and reproductive growth. Crop Protection, 27(8), 1174–1186. https://doi.org/10.1016/j.cropro.2008.02.003.

112

Valdés-Gómez

, Gary

, Cartolaro

, Lolas-Caneo

, Calonnec

, 2011. Powdery mildew development is positively influenced by grapevine vegetative growth induced by different soil management strategies. Crop Protection, 30(9), 1168–1177. https://doi.org/10.1016/j.cropro.2011.05.014.

113

Varga

, Májer

, Jahnke

G. G.

, Németh

, Szoke

, Sárdi

, … Salamon

, 2012. Adaptive Nutrient Supply and Soil Cultivation Methods in the Upper Zone of Hillside Vineyards. Communications in Soil Science and Plant Analysis, 43(1–2), 334–340. https://doi.org/10.1080/00103624.2012.641463.

114

Vivai Cooperativi Rauscedo

, 2013. Catálogo general de las variedades y los clones de uva de vino y de mesa. Udine, Italia.

115

Vogelweith

, Thiéry

, 2017. Cover crop differentially affects arthropods, but not diseases, occurring on grape leaves in vineyards. Australian Journal of Grape and Wine Research, 23(3), 426–431. https://doi.org/10.1111/ajgw.12290.

116

Vrsic

, Ivancic

, Pulko

, Valdhuber

, 2011. Effect of soil management systems on erosion and nutrition loss in vineyards on steep slopes. Journal of Environmental Biology, 32(3), 289–294..

117

Vukicevich

, Thomas Lowery

, Úrbez-Torres

J. R.

, Bowen

, Hart

, 2018. Groundcover management changes grapevine root fungal communities and plant-soil feedback. Plant and Soil, 424(1–2), 419–433. https://doi.org/10.1007/s11104-017-3532-2.

118

Wheeler

S. J.

, Black

A. S.

, Pickering

G. J.

, 2005. Vineyard floor management improves wine quality in highly vigorous vitis vinifera 'Cabernet-Sauvignon' in New Zealand. New Zealand Journal of Crop and Horticultural Science, 33(3), 317–328. https://doi.org/10.1080/01140671.2005.9514365.

119

Wilson

, Miles

A. F.

, Daane

K. M.

, Altieri

M. A.

, 2017. Landscape diversity and crop vigor outweigh influence of local diversification on biological control of a vineyard pest. Ecosphere, 8(4). https://doi.org/10.1002/ecs2.1736.

120

Wolff

M. W.

, Alsina

M. M.

, Stockert

C. M.

, Khalsa

S. D. S.

, Smart

D. R.

, 2018. Minimum tillage of a cover crop lowers net GWP and sequesters soil carbon in a California vineyard. Soil and Tillage Research, 175, 244–254. https://doi.org/10.1016/j.still.2017.06.003.

121

Z.-M.

, Tao

Y.-S.

, Zhang

, Li

, 2011. Impact of cover crops in vineyard on the aroma compounds of Vitis vinifera L. cv Cabernet-Sauvignon wine. Food Chemistry, 127(2), 516–522. https://doi.org/10.1016/j.foodchem.2011.01.033.

122

, Zhang

, Cheng

, Li

, 2010. The Effect of Vineyard Cover Crop on Main Monomeric Phenols of Grape Berry and Wine in Vitis viniferal L. cv. Cabernet-Sauvignon. Agricultural Sciences in China, 9(3), 440–448. https://doi.org/10.1016/S1671-2927(09)60115-2.